C/C++: for循环

I. 用嵌套for循环来实现一些字母或符号的有趣图形：

1.打印如下的符号：

$$$$$$$$$$$$$$$test1.c:#include<stdio.h>#include<stdlib.h>#define a 5#define b 5int main(void){ int i,j; for (i=a;i>0;i--)  {  for (j=0;j<(b-i)+1;j++)    {    printf ("$");    }  printf ("\n"); }system("pause");return 0;}

2.用字母打印如下图形：

FFEFEDFEDCFEDCBFEDCBAtest2.c:#include <stdio.h>#include <stdlib.h>int main(void){  int char_a='F';  int a,b;  for (a=char_a;a>='A';a--)  //外层循环    {    for (b=char_a;b>=a;b--)  //内层循环    {      printf ("%c",b);    }     printf ("\n");   }  system("pause");  return 0; }

3.打印如下图形：

ABCDEFGHIJKLMNOPQRSTUtest3.c:#include<stdio.h>#include <stdlib.h>int main(void)   {   char array[27] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";   int i, j,index;   for (i = 0,index=0 ; i < 6; i++)      {      for (j = 0; j <= i; j++,index++)         {         printf ("%c",array[index]);         }       printf ("\n");      }   system ("pause");   return 0;   }

4.

    A   ABA  ABCBA ABCDCBAABCDEDCBAtest4.c:#include<stdio.h>int main(void){    char lets[27] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";    char letter;    int out_i, in_i_black, in_i_up, in_i_down;    printf("please Enter a letter (for example: E ):\n");    scanf("%c",&letter);    for (out_i = 0; lets[out_i] <= letter; out_i++)    {        for (in_i_black = 0; in_i_black < (letter - lets[out_i]); in_i_black++)        {            putchar(' ');        }        for (in_i_up = 0; in_i_up < out_i;in_i_up++)        {            putchar(lets[in_i_up]);        }        for (in_i_down = out_i; in_i_down >= 0;in_i_down--)        {            putchar(lets[in_i_down]);        }        putchar('\n');    }    getchar();    getchar();    return 0;}