expeval.cpp: In function 'int pol()': expeval.cpp:49: warning: comparison between signed and unsigned integer expressions expeval.cpp:47: warning: unused variable 'a' expeval.cpp: In function 'int main()': expeval.cpp:126: warning: comparison between signed and unsigned integer expressions expeval.cpp:122: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result expeval.cpp:123: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result expeval.cpp:125: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result expeval.cpp: In function 'int calc(int, int, char)': expeval.cpp:44: warning: control reaches end of non-void function