菜鸟学C：输出金字塔

[root@localhost unit6]# cat test4.c 
#include <stdio.h>
int main(void)
{
        char a;
        printf("Please enter:");
        scanf("%c",&a);

        int i,j,m,n;
        for(i = 1; i <= 5; i++){
                char b = a;
                for(j = 5 - i; j >=1; j--){
                        printf(" ");
                }
                for(m = i - 1; m >= 1; m--){
                        printf("%c",b - m);
                }
                printf("%c",a++);
                for(n = 1; n < i; n++){
                        printf("%c",b - n);
                }
                printf("\n");
        }
        return 0;
}