c语言，才疏学浅没有思路

Question

c语言初学者，没有思路，帮忙看看？比较急，下午要讲，求指点，感激不尽！

Answer 1

供参考：

#include <stdio.h>
void print_pattern1(int n)
{
    int  i, j;
    char ch = 'a';
    printf("Pattern I\n");
    for (i = 0; i < n; i++)
    {
        for (j = 0, ch = 'a'; j <= i; j++)
            printf("%-2c", ch++);
        printf("\n");
    }
}
void print_pattern2(int n)
{
    int  i, j;
    char ch = 'a';
    printf("Pattern II\n");
    for (i = 0; i < n; i++)
    {
        for (j = 0, ch = 'a'; j < n - i; j++)
            printf("%-2c", ch++);
        printf("\n");
    }
}
void print_pattern3(int n)
{
    int  i, j;
    char ch;
    printf("Pattern III\n");
    for (i = 0; i < n; i++)
    {
        for (j = 0; j < n - i - 1; j++)
            printf("  ");
        for (j = 0, ch = 'a' + i; j <= i; j++)
            printf("%-2c", ch--);
        printf("\n");
    }
}
void print_pattern4(int n)
{
    int  i, j;
    char ch = 'a';
    printf("Pattern IV\n");
    for (i = 0; i < n; i++)
    {
        for (j = 0, ch = 'a' + n - 1 - i; j < n - i; j++)
            printf("%-2c", ch--);
        printf("\n");
    }
}
int main()
{
    int ch = 1, n;
    while (ch) {
        printf("Which pattern would you like to print?\n");
        printf("--------------------------------------\n");
        scanf("%d", &ch);
        switch (ch) {
        case 1:printf("input line n:"); scanf("%d", &n); print_pattern1(n); break;
        case 2:printf("input line n:"); scanf("%d", &n); print_pattern2(n); break;
        case 3:printf("input line n:"); scanf("%d", &n); print_pattern3(n); break;
        case 4:printf("input line n:"); scanf("%d", &n); print_pattern4(n); break;
        case 5:ch = 0; break;
        default:break;
        }
    }
    return 0;
}