Calling a function before declaring its prototype or including header file.
In C99 and newer C standards, calling a function without a prior prototype declaration is an error or warning.
Forgetting to include `#include <stdio.h>` or `#include <stdlib.h>`, or placing function call above its definition without a header declaration.
1// Missing: #include <stdio.h>2 3int main() {4 printf("Hello World\n"); // Error: implicit declaration of function 'printf'5 return 0;6}1#include <stdio.h> // Include proper header2 3int main() {4 printf("Hello World\n");5 return 0;6}Simulate standard system builds to trigger compiler trace records and track memory crashes locally.
Without `#include <stdio.h>`, compiler does not know parameter signature or return type of `printf`.