打印字母及其ascii代码

use*_*300 1 c

我尝试打印从A到Z以及从a到z及其ascii代码的所有字母,但当我尝试运行它时,我最终得到一个无限循环,那么错误在哪里?

#include <stdio.h>

int main(void) {
 int i;
 char ch_1,ch_2;

 for (ch_1='A'; ch_1<='Z'; ch_1++) printf("letter: %c ASCII code:%d\n",ch_1,ch_1);
 for (ch_2='a'; ch_1<='z'; ch_2++) printf("letter: %c ASCII code: %d\n",ch_2,ch_2);
}
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MOH*_*MED 9

for (ch_2='a'; ch_2<='z'; ch_2++)
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and not

for (ch_2='a'; ch_1<='z'; ch_2++)
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