replace.cpp: In function 'int main()': replace.cpp:12: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result replace.cpp:15: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result replace.cpp:19: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result