Compilare: main.cpp: In function 'matrix operator*(matrix, matrix)': main.cpp:25:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a.height;i++){ ~^~~~~~~~~ main.cpp:26:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<b.width;j++){ ~^~~~~~~~ main.cpp:27:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=0;k<a.width;k++){ ~^~~~~~~~