added dump, makefile todo

TODO.md

@@ -1,3 +1,4 @@
 # TODO
 ### This file contains ideas for new small projects i would like to add to this repo.
 calculate big exponents, factorials
+fix damn makefile, it compiles only abc.c into all the binaries

dump.c

@@ -0,0 +1,42 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct a {
+    int a;
+    char str[30];
+};
+
+/*
+ * give an argument to keep the file /tmp/structdump
+ * like this: bin/dump aaa
+ */
+
+int main(int argc, char** argv){
+    struct a* mystruct = malloc(sizeof(struct a));
+    if(mystruct == NULL){
+        printf("malloc for 1st struct failed!\n");
+        return 1;
+    }
+    mystruct->a = 12;
+    char s[30] = "Wer das liest ist doof";
+    strcpy(mystruct->str, s);
+    FILE* fptr = fopen("/tmp/structdump", "wb");
+    fwrite(mystruct, sizeof(struct a), 1, fptr);
+    fclose(fptr);
+    free(mystruct);
+
+    fptr = fopen("/tmp/structdump", "rb"); 
+    mystruct = malloc(sizeof(struct a));
+    if(mystruct == NULL){
+        printf("malloc for 2nd struct failed!\n");
+        return 1;
+    }
+    fread(mystruct, sizeof(struct a), 1, fptr); 
+    printf("mystruct->a: %d\nmystruct->str: \"%s\"\n", mystruct->a, mystruct->str);   // SIGSEV
+    free(mystruct);
+    fclose(fptr);
+    if(argc<2)
+        remove("/tmp/structdump");
+    return 0;
+}