gistfile1.txt

#import <Foundation/Foundation.h>

void eachrow(size_t nrows, size_t ncols, char const*** rows, BOOL(^cb)(size_t i, size_t ncols, char const **row, size_t *lengths))
{
    size_t lengths[ncols];
    for (size_t i = 0; i < nrows; ++i)
    {
        for (size_t j = 0; j < ncols; ++j)
        {
            lengths[j] = strlen(rows[i][j]);
        }
        if (!cb(i, ncols, rows[i], lengths)) break;
    }
}

static void print_int(char const *s, size_t l)
{
    printf("%d, ", atoi(s));
}

static void print_string(char const *s, size_t l)
{
    printf("%.*s, ", (int)l, s);
}

static void print_float(char const *s, size_t l)
{
    printf("%f\n", atof(s));
}

int main(int argc, const char * argv[])
{
    __block struct
    {
        void (*fptrs[3])(char const *, size_t);
    }
    ctx;
    eachrow(3, 3, (char const **[]){
        (char const *[]){ "1", "hello", "3.14" },
        (char const *[]){ "2", "pony",  "2.72" },
        (char const *[]){ "3", "world", "1.62" },
    }, ^(size_t i, size_t ncols, char const **row, size_t *lengths)
    {
        if (i == 0)
        {
            ctx.fptrs[0] = print_int;
            ctx.fptrs[1] = print_string;
            ctx.fptrs[2] = print_float;
        }
        
        for (size_t col = 0; col < ncols; ++col)
        {
            ctx.fptrs[col](row[col], lengths[col]);
        }
        
        return YES;
    });
    return 0;
}