expeval.cpp: In function 'int main()': expeval.cpp:148: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result expeval.cpp:149: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result expeval.cpp:151: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result expeval.cpp: In function 'void expeval()': expeval.cpp:66: warning: 'x' may be used uninitialized in this function