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upload of older code

This commit is contained in:
Christoph J. Scherr 2022-11-24 21:04:54 +01:00
parent 121b165551
commit c463b342fa
33 changed files with 907 additions and 0 deletions
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29
7-teiler.c Normal file
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/*
* lower and upper end as user input
* use a for loop to output all numbers for which 7|x is true.
*/
#include <stdio.h>
int main() {
int a,b;
printf("input lower end:\n");
fflush(stdin);
scanf("%d",&a);
printf("input upper end:\n");
fflush(stdin);
scanf("%d",&b);
printf("inputs: %d %d\n", a, b);
for(int i=a; i<=b; i++){
if(i%7==0)
printf("%d ", i);
if(i==b)
printf("\n");
}
// reverse array order
return 0;
}

27
7teiler.c Normal file
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/*
* lower and upper end as user input
* use a for loop to output all numbers for which 7|x is true.
*/
#include <stdio.h>
int main() {
int a,b;
printf("input lower end:\n");
fflush(stdin);
scanf("%d",&a);
printf("input upper end:\n");
fflush(stdin);
scanf("%d",&b);
printf("inputs: %d %d\n", a, b);
for(int i=a; i<=b; i++){
if(i%7==0)
printf("%d ", i);
if(i==b)
printf("\n");
}
return 0;
}

27
abc.c Normal file
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#include <stdio.h>
#include <math.h>
#include <complex.h>
#include <stdlib.h>
int main(int argc, char **argv){
if(argc<3){
printf("not enough args! Ex: ./abc 12 -3 5\n");
exit(EXIT_FAILURE);
}
double a = atoi(argv[1]);
double b = atoi(argv[2]);
double c = atoi(argv[3]);
printf("(%f)x²+(%f)x+(%f)=0\n", a, b, c);
double l1 = 0, l2 = 0;
double cl1 = 0, cl2 = 0;
l1=(-b + sqrt((b*b)-(4*a*c)))/(2*a);
l2=(-b - sqrt((b*b)-(4*a*c)))/(2*a);
cl1=(-b + csqrt((b*b)-(4*a*c)))/(2*a);
cl2=(-b - csqrt((b*b)-(4*a*c)))/(2*a);
printf("(-%.0f (+-) sqrt[(%.0f²)-(4*%.0f*%.0f)])/2*%.0f\n", b, b, a, c, a);
printf("x1=%f x2=%f\n", l1, l2);
printf("(complex mode)\nx1=%fi\tx2=%fi\n", cl1, cl2);
return 0;
}

9
adder.c Normal file
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#include <stdio.h>
int main() {
int a, b;
printf("Please input two integers to be added.\n");
scanf("%d %d", &a, &b);
printf("%d + %d = %d\n", a, b, a+b);
return 0;
}

15
args.c Normal file
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#include <stdio.h>
int main(int argc, char* argv[]){
if(argc==1){
printf("Recieved only one argument, idiot");
return 1;
}
for(int i = 0; i < argc+1; i++){
printf("%d. [%s]\n", i+1, argv[i]);
}
return 0;
}

29
arrToBin.c Normal file
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#include <stdio.h>
#include <stdlib.h>
int main(){
// input as single int, output as array of ints with only 0 and 1s
char str_i[20];
int i;
fgets(str_i, 20, stdin);
i = strtol(str_i, NULL, 0);
printf("%d", i);
int bin[16] = { -1 };
int b;
printf("[CONTROL]as hex %x\n", i);
for(int j = 16; j>0; j--){
b = i%2;
i /= 2;
bin[i] = b;
}
for(int j = 0; j < 16; j++){
if(
printf("%d", bin[j]);
}
printf("\n");
return 0;
}

8
ascii.c Normal file
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#include <stdio.h>
int main(){
for(int i=0; i<256; i++){
printf("(dec)%d\t(hex)0x%02x\t(char)%c\t\n",i,i,i);
}
return 0;
}

49
calculator.c Normal file
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#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
double factorial(double i) {
if(i <= 1) {
return 1;
}
return i * factorial(i - 1);
}
double power(double a, double b) {
double result = a;
for(int i=0;i<b;i++){
result*=a;
}
return result;
}
int main(int argc, char **argv){
// inputs
uint32_t a, b;
char op;
while(1) {
printf("\nPlease input the first number.\n");
fflush(stdin);
scanf("%d", &a);
printf("Please input the second number.\n");
fflush(stdin);
scanf("%d", &b);
printf("Please select an operation. ( + - * / ^ ! ), e to exit.\n");
fflush(stdin);
scanf(" %c", &op); //The %c conversion specifier won't automatically skip any leading whitespace
// calculate stuff.
switch(op) {
case '+': printf("%d + %d = %d\n", a, b, a+b); break;
case '-': printf("%d - %d = %d\n", a, b, a-b); break;
case '*': printf("%d * %d = %d\n", a, b, a*b); break;
case '/': printf("%d / %d = %f\n", a, b, (double)a/(double)b); break;
case '^': printf("%d^%d = %f\n", a, b, power((double)a,(double)b)); break;
case '!': printf("%d! = %f\n", a, factorial((double)a)); break;
case 'e': printf("exiting...\n"); return 0;
//case '%': printf("%d % %d = %d\n", a, b, a%b); break; // idk weird outputs.
default: printf("no operation recognized.\n"); return 1;
}
}
}

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callreference.c Normal file
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#include <stdio.h>
int* ref(int *i, int* j, int* result){
*result = *i + *j;
return result;
}
int val(int a, int b){
return a+b;
}
int main(){
int x = 1000;
int y = 337;
int z;
printf("given: %d\n", x);
printf("reference: %d\n", *ref(&x, &y, &z));
printf("value: %d\n", val(x, y));
return 0;
}

83
complex.c Normal file
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#include <stdio.h>
typedef struct
{
float real;
float imaginary;
}complex;
complex assignComplex(){
float r, i;
scanf("%f", &r);
scanf("%f", &i);
complex c;
c.real = r;
c.imaginary = i;
return c;
}
void addComplex() {
printf("First complex\n");
complex a = assignComplex();
printf("Second complex\n");
complex b = assignComplex();
complex r;
r.real = a.real + b.real;
r.imaginary = a.imaginary + b.imaginary;
printf("Result: %f+%fi\n", r.real, r.imaginary);
}
void subComplex() {
printf("First complex\n");
complex a = assignComplex();
printf("Second complex\n");
complex b = assignComplex();
complex r;
r.real = a.real - b.real;
r.imaginary = a.imaginary - b.imaginary;
printf("Result: %f+%fi\n", r.real, r.imaginary);
}
void mulComplex() {
printf("First complex\n");
complex a = assignComplex();
printf("Second complex\n");
complex b = assignComplex();
complex r;
r.real = a.real * b.real;
r.imaginary = a.imaginary * b.imaginary;
printf("Result: %f+%fi\n", r.real, r.imaginary);
}
void divComplex() {
printf("First complex\n");
complex a = assignComplex();
printf("Second complex\n");
complex b = assignComplex();
complex r;
r.real = a.real / b.real;
r.imaginary = a.imaginary / b.imaginary;
printf("Result: %f+%fi\n", r.real, r.imaginary);
}
int main() {
printf("Usage:\n\toperations: + - * /\n\tquit: q\n");
char in;
while(1){
in = getchar();
switch(in){
case 'q': return 0;
case '+': addComplex(); break;
case '-': subComplex(); break;
case '*': mulComplex(); break;
case '/': divComplex(); break;
default: printf("kaputt\n"); break;
}
}
}

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echo.c Normal file
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#include <stdio.h>
int main() {
char s[100];
gets(s);
printf("%s\n", s);
return 0;
}

8
echochar.c Normal file
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#include <stdio.h>
int main() {
char a = getchar();
printf("%c", a);
return 0;
}

50
euler.c Normal file
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#include <stdio.h>
#include <stdio.h>
#include <stdlib.h>
// range of unsigned long long is:
// 18.446.744.073.709.551.615
// maximum factorial with this is 65!
// Double goes up to 170!
double factorial(double i) {
if(i <= 1) {
return 1;
}
return i * factorial(i - 1);
}
double factorialFor(double given){
double p = 1;
// someone said i need 2 for loops. Totally wrong?
for(int j=1;j<given;j++){
p *= j;
//printf("[DEBUG]p is %f, j is %d\n", p, j);
}
return given * p;
}
double euler(int k) {
return 1/factorial(k);
}
int main(int argc, char *argv[]){
double res = 0, lres = 0;
int k = 0;
int end = 0;
while(!end){
res += euler(k);
printf("%f, %f\n", res, lres);
if(res==lres)
end = 1;
else {
lres = res;
}
k++;
}
printf("calculated eulers number as %f\n", res);
return 0;
}

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factorial.c Normal file
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#include <stdio.h>
#include <stdlib.h>
// range of unsigned long long is:
// 18.446.744.073.709.551.615
// maximum factorial with this is 65!
// Double goes up to 170!
double factorial(double i) {
if(i <= 1) {
return 1;
}
return i * factorial(i - 1);
}
double factorialFor(double given){
double p = 1;
// someone said i need 2 for loops. Totally wrong?
for(int j=1;j<given;j++){
p *= j;
//printf("[DEBUG]p is %f, j is %d\n", p, j);
}
return given * p;
}
int main(int argc, char *argv[]){
if(argc<=1) {
printf("You did not feed me arguments, I will die now :( gimme ints");
return 1;
} //otherwise continue on our merry way....
double num = atoi(argv[1]);
printf("the factorial of the given input calculated by a recursive algorithm is: %.0f\n", factorial(num));
printf("the factorial of the given input calculated by a nonrecursive algorithm is: %.0f\n", factorialFor(num));
return 0;
}

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fread.c Normal file
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#include <stdio.h>
#include <string.h>
int main () {
FILE *fp;
char c[] = "this is tutorialspoint";
char buffer[100];
/* Open file for both reading and writing */
fp = fopen("file.txt", "w+");
/* Write data to the file */
fwrite(c, strlen(c) + 1, 1, fp);
/* Seek to the beginning of the file */
fseek(fp, 0, SEEK_SET);
/* Read and display data */
fread(buffer, strlen(c)+1, 1, fp);
printf("%s\n", buffer);
fclose(fp);
return(0);
}

6
hello-world.c Normal file
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#include <stdio.h>
int main() {
printf("Hello world!\n");
return 0;
}

247
huffman/huffman.c Normal file
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#include <errno.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
off_t fsize(const char *filename) {
struct stat st;
if (stat(filename, &st) == 0)
return st.st_size;
fprintf(stderr, "Cannot determine size of %s: %s\n", filename,
strerror(errno));
return -1;
}
void helper() {
printf("huffman compression algorithm implementation for educational "
"purposes.\n\nSyntax:\nhuffman -f fileToCompress\t\tcompress the "
"given file\nhuffman -xf fileToDecompress\t\tdecompress the given "
"file\nhuffman -h\t\t\t\tshow this help\nhuffman -v\t\t\t\tverbose\n");
}
int main(int argc, char *argv[]) {
int opt;
bool extract_mode = false;
bool verbose = false;
bool debug = false;
char *filestring = NULL;
uint64_t filelen;
FILE *fptrR = NULL; // file pointer for reading
FILE *fptrW = NULL; // file pointer for writing
while ((opt = getopt(argc, argv, "dvxhf:")) != -1) {
if (debug)
printf("optarg is: %s\n", optarg);
switch (opt) {
case 'v':
verbose = true;
break;
case 'd':
debug = true;
break;
case 'f':
filestring = optarg;
break;
case 'h':
helper();
exit(0);
break;
case 'x':
extract_mode = true;
break;
default:
fprintf(stderr, "Usage: %s [-dvhx -f] [file]\n", argv[0]);
exit(EXIT_FAILURE);
}
}
// Now optind (declared extern int by <unistd.h>) is the index of the first
// non-option argument. If it is >= argc, there were no non-option arguments.
if (verbose)
printf("selected file: %s\n", filestring);
if (filestring) {
if(debug)
printf("[DEBUG]processing given file argument.\n");
// open the given file in binary mode, I want this to work with any files,
// not just textfiles.
fptrR = fopen(filestring, "rb");
if (fptrR == NULL) {
fprintf(stderr, "The given file does not exist or is unavailable.\n");
exit(EXIT_FAILURE);
}
// causes bugs.
fseek(fptrR, 0L, SEEK_END);
filelen = ftell(fptrR);
fseek(fptrR, 0L, SEEK_SET);
}
else {
// empty filestring or filestring is NULL
fprintf(stderr, "Usage: %s [-dvhx -f] [file]\n", argv[0]);
exit(EXIT_FAILURE);
}
// TODO check file size and spit a "what the heck im not a 10x dev, do a
if(verbose)
printf("filesize: %ldB\n", filelen);
if (extract_mode) {
printf("extracting is not yet implemented.\n");
// decompress the file
}
else {
// compress the file
if (verbose)
printf("compressing file...\n");
// frequency analysis
uint8_t buf[512];
// dump start of file if debugging
// FIXME add conditions if the part to print is smaller than 512B
if(debug){
printf("[DEBUG]First 512 bytes are:\n");
fread(buf, 1, 512, fptrR);
for(int i=0;i<512;i++){
if(i%16==0)
printf("%08x\t", i);
printf("%02x ", buf[i]);
if(i%16==7)
printf(" ");
if(i%16==15){
printf("\n");
}
}
}
uint64_t occurences[256];
for(int i=0;i<256;i++){
occurences[i]=0;
}
// FIXME doesnt loop through full file! only 50% for larger files
// Backup occurence counting algorithm
/*
while(!feof(fptrR)){
fseek(fptrR, 512, SEEK_CUR);
if(fread(buf, 1, 512, fptrR)){
for(int i=0;i<512;i++){
occurences[buf[i]]++;
}
}
else{
fprintf(stderr, "Error when processing file.\n");
exit(EXIT_FAILURE);
}
// advance filepointer 512 bytes foreward. If not possible, set endOfFile flag.
// FIXME
offset += 512;
}
*/
// backup
/*
while(1){
fseek(fptrR, 512, SEEK_CUR); // this line seems the be making the most problems
// On success, fread() and fwri)te() return the number of items read or written.
// This number equals the number of bytes transferred only when size is
// 1. If an error occurs, or the end of the file is reached, the return value is a short item count (or zero).
// fread() does not distinguish between end-of-file and error, and callers must use feof(3) and ferror(3) to determine which occurred.
// FIXME )This is a buggy mess
if(512 == fread(buf, 1, 512, fptrR)){
for(int i=0;i<512;i++){
occurences[buf[i]]++;)
}
})
else if(0 == fread(buf, 1, 512, fptrR)){
if(debug)
printf("[DEBUG]fread returned 0! ftell for current position is %lu\n", ftell(fptrR));
break;
}
else{
fprintf(stderr, "Error when processing file: %lu, At offset %lu\n",fread(buf, 1, 512, fptrR), ftell(fptrR));
exit(EXIT_FAILURE);
}
if(ftell(fptrR) > filelen) {
// ??? unknown error
fprintf(stderr, "tried reading further than the file is long somehow?\n");
exit(EXIT_FAILURE);
}
}
*/
// ALMOST WORKS! ~200 bytes lost for a 10M file!!!
uint8_t bufMini[1];
while(1){
if(fread(bufMini, 1, 1, fptrR)){
occurences[buf[0]]++;
}
else{
if(ferror(fptrR)){
fprintf(stderr, "encountered error when reading file.\n");
exit(EXIT_FAILURE);
}
}
fseek(fptrR, 1, SEEK_SET);
if(ferror(fptrR)){
fprintf(stderr, "encountered error when reading file.\n");
exit(EXIT_FAILURE);
}
else if(feof(fptrR)){
continue;
}
}
if(debug){
printf("Occurences (Hex):\n");
for(int i=0;i<256;i++){
if(i%4==0)
printf("\n");
printf("0x%02x: %016lx\t", i, occurences[i]);
}
printf("\n\nfile length(by pointer):\t\t%luB\n", filelen);
long long int addedUpOccurences = 0; // FIXME might not be enough storage for larger files!
for(int i=0;i<256;i++){
addedUpOccurences += occurences[i];
}
printf("file length(added up occurences):\t%lldB\n", addedUpOccurences);
}
if(verbose)
printf("\n\nDone calculating occurences of bytes.\n");
// TODO
// calculate the frequencies of the bytes.
double frequencies[256];
for(int i=0;i<256;i++){
frequencies[i]=((double)occurences[i]/(double)filelen)*100; // calculate frequencies of bytes in percent (example: 05.23 (%))
}
if(debug){
printf("Frequencies:\n");
for(int i=0;i<256;i++){
if(i%8==0)
printf("\n");
printf("0x%02x: %05.02f%%\t", i, frequencies[i]);
}
double addedUpFrequencies = 0;
for(int i=0;i<256;i++){
addedUpFrequencies += frequencies[i];
}
printf("\n\nadded up frequencies: %05.02f%%\n",addedUpFrequencies);
}
}
fclose(fptrR);
printf("\n");
exit(EXIT_SUCCESS);
}

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options.c Normal file
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#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
bool isCaseInsensitive = false;
int opt;
enum { CHARACTER_MODE, WORD_MODE, LINE_MODE } mode = CHARACTER_MODE;
while ((opt = getopt(argc, argv, "ilw")) != -1) {
switch (opt) {
case 'i': isCaseInsensitive = true; break;
case 'l': mode = LINE_MODE; break;
case 'w': mode = WORD_MODE; break;
default:
fprintf(stderr, "Usage: %s [-ilw] [file...]\n", argv[0]);
exit(EXIT_FAILURE);
}
}
// Now optind (declared extern int by <unistd.h>) is the index of the first non-option argument.
// If it is >= argc, there were no non-option arguments.
}

9
pointer-arithmetic.c Normal file
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#include <stdio.h>
int main() {
int a[5] = {22, 33, 44, 55, 66};
int *ptr = NULL;
ptr = a; /* point to the first array element */
for(int i = 0; i < 50; i++) {
printf(" value:0x%-10x\tor 0d%-16d\tAdress:%-8x\n", *(ptr+i), *(ptr+i), ptr+i); /* 33 */
}}

19
pointermagic.c Normal file
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#include <stdio.h>
void printLoc(int y) {
printf("Address of y is %x\n", &y);
}
void printPointerLoc(int *x) {
printf("Adress of x is %x\n", &x);
printf("Adress the x pointer points to is %x\n", x);
printf("Adress of whatever *x is is %x\n", *x);
}
int main() {
int a = 0xAAAA;
printf("Address of a is %x\n", &a);
printLoc(a);
printPointerLoc(&a);
return 0;
}

43
primenumbers.c Normal file
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#include <stdio.h>
#include <stdlib.h>
int main(int argc, char** argv) {
int maxPrime = atoi(argv[1]);
int *arr1 = malloc(sizeof(int)*maxPrime);
if(arr1==NULL)
return -1;
for(int i=0; i<maxPrime; i++) {
arr1[i]=i+2;
}
int p = 2;
for(int i=1; i<maxPrime; i++) {
for(int j=1; j<maxPrime; j++) {
if((arr1[j]%p==0)&&(arr1[j]>0)&&(arr1[j]!=p))
arr1[j]=-1;
}
// get next prime in arr
// FIXME
p = arr1[i];
for(int l=0;l<512;l++){
if(p>0)
break;
else {
p = arr1[i+l];
}
}
for(int l=0;l<maxPrime;l++){
}
}
printf("\n");
printf("\n");
for(int i=0;i<maxPrime;i++){
if(arr1[i]>0)
printf("%d ", arr1[i]);
}
free(arr1);
printf("\n");
return 0;
}

30
quersumme.c Normal file
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#include <stdio.h>
int main() {
int a, digits = 0, b = 0;
printf("input a number for calculation\n");
fflush(stdin);
scanf("%d",&a);
int digit[128];
// look out for wrong order
for(int i=0; i<128; i++) {
digit[i] = a % 10;
if(a>0)
a = a / 10;
else {
if(digits==-1)
digits = i;
digit[i] = -1;
}
//printf("%d. digit is: %d\n", i, digit[i]);
}
// array is in wrong order, but who cares for the quersumme
for(int i=0; i<128; i++){
if(digit[i]>0)
b += digit[i];
}
printf("quersumme is: %d\n", b);
return 0;
}

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readfile.c Normal file
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#include <stdlib.h>
#include <stdio.h>
int main(void)
{
char filename[] = "file.txt";
char buf[2];
FILE *fp;
if ((fp = fopen(filename, "rb")) == NULL)
{
printf("Unable to open file: %s\n", filename);
return EXIT_FAILURE;
}
if (fread(buf, 1, 2, fp) == 2)
{
printf("%02x %02x\n", (int) buf[0], (int) buf[1]);
}
fclose(fp);
return 0;
}

8
redefinition-if.c Normal file
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#include <stdio.h>
int main() {
int a;
if(1){
int a; // works, this a is only in scope of the if statement.
}
return 0;
}

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redefinition.c Normal file
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#include <stdio.h>
int a = 1;
int main() {
int a = 2;
printf("%d\n", a); // local overrides global
return 0;
}

10
scanf-test.c Normal file
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#include <stdio.h>
int main() {
int a;
float f;
char s[20];
scanf("%d %f %s", &a, &f, s);
printf("%d %f %s\n", a, f, s);
return 0;
\n}

8
scnaf-hex-test.c Normal file
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#include <stdio.h>
int main() {
int a;
scanf("%x", &a);
printf("hex: %x dec: %d\n", a, a);
return 0;
}

6
signed-to-unsigned.c Normal file
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#include <stdio.h>
int main() {
signed int a = -1;
printf("%u\n",a); // no need to type cast. %u interprets given bytes of type unsigned int regardless of the datatype. truly low level
}

10
sizeofs.c Normal file
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#include <stdio.h>
int main() {
printf("int: %ld \n", sizeof(int));
printf("float: %ld \n", sizeof(float));
printf("double: %ld \n", sizeof(double));
printf("char: %ld \n", sizeof(char));
return 0;
}

11
sum.c Normal file
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#include <stdio.h>
int main(){
int result = 0;
for (int i = 1; i < 101; i++){
result+=i;
}
printf("sum of 1 up to 100 is: %d\n", result);
return 0;
}

8
tabtest.c Normal file
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#include <stdio.h>
int main() {
printf("horizontal\ttab\n");
printf("vertical%ctab\n", 11);
printf("reference line\n");
return 0;
}

3
umlaut.c Normal file
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#include <stdio.h>
int main() { return 0; }
int zähler() { return 0; } // umlaute is an unknown char for gcc

6
unary-double-not.c Normal file
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#include <stdio.h>
int main(){
printf("%d\n",!!42);
return 0;
}