Compilare: main.cpp: In function 'int main()': main.cpp:34:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(l=0;l<strlen(celule[i][j].formula);l++) ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:60:88: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(celule[i][j].formula[l]>='0' && celule[i][j].formula[l]<='9' && l<strlen(celule[i][j].formula)) ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~