Compilare: user.cpp: In function ‘int calc(char*, int)’: user.cpp:11:10: warning: unused variable ‘c’ [-Wunused-variable] char c; ^ user.cpp: In function ‘int main()’: user.cpp:38:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=2; j<=strlen(sir); j++) ^ user.cpp:50:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=1;j<=strlen(sir);j++) ^ user.cpp:32:22: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&z); ^ user.cpp:36:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"\n%s",sir); ^