Question

I’m printing debug statements for a 4×4 matrix. Does anyone know of a better way to do this, without using cout?

// num decimal places to show
void print( int decimals )
{
    char fmtString[ 300 ] ;

    // I'm thinking this should be able to get smaller.
    sprintf(fmtString,
            "%%.%df %%.%df %%.%df %%.%df\n"
            "%%.%df %%.%df %%.%df %%.%df\n"
            "%%.%df %%.%df %%.%df %%.%df\n"
            "%%.%df %%.%df %%.%df %%.%df",
            decimals, decimals, decimals, decimals, 
            decimals, decimals, decimals, decimals, 
            decimals, decimals, decimals, decimals, 
            decimals, decimals, decimals, decimals ) ;

    printf(fmtString,
           m[0][0], m[0][1], m[0][2], m[0][3],
           m[1][0], m[1][1], m[1][2], m[1][3],
           m[2][0], m[2][1], m[2][2], m[2][3],
           m[3][0], m[3][1], m[3][2], m[3][3] ) ;
}

Super bonus points for preprocessor!

Answer 1

How about:

void print( int decimals = 2 )
{
    int dimension = 4;
    for(int i = 0; i < dimension; i++) {
        for(int j = 0; j < dimension; j++) {
            printf("%.*f", decimals, matrix[i][j]);
            if(j == dimension - 1) printf("\n");
            else                   printf(" ");
        }
    }
}