Compilare: main.cpp: In function 'int main()': main.cpp:48:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (index < exp.size() && exp[index] != '=') { ~~~~~~^~~~~~~~~~~~ main.cpp:53:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (index < exp.size()) { ~~~~~~^~~~~~~~~~~~ main.cpp:38:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ecuatii2.in", "r", stdin); ^ main.cpp:39:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ecuatii2.out", "w", stdout); ^ main.cpp:42:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^