Compilare: main.cpp: In function 'int verif(int)': main.cpp:13:8: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] s[l]=NULL; m=0; ^~~~ main.cpp:14:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i+l-1<strlen(a[1]);i++){ ~~~~~^~~~~~~~~~~~~ main.cpp:16:45: warning: converting to non-pointer type 'char' from NULL [-Wconversion-null] strcpy(s,s+1); s[l-1]=a[1][i+l-1]; s[l]=NULL; ^~~~