c语言中的二重循环

#include <stdio.h>

int main(void)
{
    int i, j;
    
    for (i = 1; i <= 9; i++)
    {
        for (j = 1; j <= 9; j++)
        {
            printf("%4d", i * j);
        }
        putchar(‘\n‘);
    }
    return 0;
}

#include <stdio.h>

int main(void)
{
    int i, j, k;
    
    for (i = 1; i <= 9; i++)
    {
        for (j = 1; j <= 9; j++)
        {
            int k = i * j;
            if (k > 40)
                break;
            printf("%4d", k);
        }
        putchar(‘\n‘);
    }
    return 0;
}

#include <stdio.h>

int main(void)
{
    int i, j;
    int height, width;
    puts("please input the height and width.");
    printf("height = "); scanf("%d", &height);
    printf("width = "); scanf("%d", &width);
    
    for (i = 1; i <= height; i++)
    {
        for (j = 1; j <= width; j++)
        {
            putchar(‘*‘);
        }
        putchar(‘\n‘);
    }
    return 0;
}

#include <stdio.h>

int main(void)
{
    int i, j, len;
    puts("please input the side length of the triangle.");
    printf("side length = "); scanf("%d", &len);
    
    for (i = 1; i <= len; i++)
    {
        for (j = 1; j <= i; j++)
        {
            putchar(‘*‘);
        }
        putchar(‘\n‘);
    }
    return 0;
}

#include <stdio.h>

int main(void)
{
    int i, j, len;
    puts("please input the side length of the triangle.");
    printf("side length = "); scanf("%d", &len);
    
    for (i = 1; i <= len; i++)
    {
        for (j = 1; j <= (len - i); j++)
        {
            putchar(‘ ‘);
        }
        for (j = 1; j <= i; j++)
        {
            putchar(‘*‘);
        }
        putchar(‘\n‘);
    }
    return 0;
}