#include int main() { char a; while (1) { printf("Press a key and then press Enter:"); a = getchar(); if ('a' <= a && a <= 'z') { //小写转大写 a = a-32; } else if ('A' <= a && a <= 'Z') { //大写转小写 a = a + 32; } else { //不是字母 printf("the charactor you input is not a alpha\n"); getchar(); //消除回车影响 continue; } printf("%c\n", a); getchar(); } return 0; }你是要c写的吗?,这是个c的