Compilare: main.cpp: In function 'int main()': main.cpp:170:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int z=0; z<=strlen(a[col+1]); z++) ~^~~~~~~~~~~~~~~~~~ main.cpp: In function 'int convert(char)': main.cpp:32:1: warning: control reaches end of non-void function [-Wreturn-type] } ^