C语言打印上下颠倒三角

一般逻辑性代码：

#include<stdio.h>


int diamond(int count,char ch){

        if(count <=0){
                printf("Count is error\n");
                return 0;
        }else{
                int i;
                int j;
                //输出字符
                int k;
                int m;
                int d = count;
                for(k=1;k<=count;k++){

                        for(i=d;i>1;i--){
                                printf(" ");
                        }
                        for(m=1;m<=(2*k-1);m++){
                                printf("%c",ch);
                        }
                        printf("\n");
                        d = d - 1;
                }
                j = 1;
                for(k=(count-1);k>=1;k--){

                        for(i=1;i<=j;i++){
                                printf(" ");
                        }
                        for(m=(2*k - 1);m>=1;m--){
                                printf("%c",ch);
                        }
                        printf("\n");
                        j= j + 1;
                }


        }
        return 0;

}


int main(void){

        diamond(5,'*');

        return 0;
}

改进的代码：

int diamond(int count,char ch){
    int i, j;
    int line = 0;
    int space_num = 0;

    if((line = 2*count - 1) <=0){
        printf("Count is error\n");
        return -1;
    }

    for(i=1; i<=line; i++) {
        space_num = (i/count)? i%count:(count-i%count);

        for(j=0; j<line-space_num; j++)
            printf("%c",(j < space_num)? 32:ch);
        printf("\n");
    }

    return 0;
}

换一种思路：

int diamond(int count,char ch){
    int row, col;
    int n;

    if((n = count - 1) < 0) {
        printf("Count is error\n");
        return -1;
    }

    for (row = -n; row <= n; row++) {
        for (col = -n; col <= n; col++)
            printf("%c", (fabs(row) + fabs(col) <= n)? ch:32); //<=改成==可以打印空心菱形

        printf("\n");
    }

    return 0;
}