C语言 字符串大小写转换

#include<stdio.h>
void main(){
	
	//键入一个字符串
	char str[10]  = {'\0'};

	printf("please enter a string ,no more than 100 characters\n");

	for(int i = 0; i < 10; i++ ){
		//循环键入赋值
		scanf("%c",&str[i]);
		printf("-------\n");
		
		if(str[i] >='A' && str[i] <= 'Z'){
			str[i] += 32;
		}else if(str[i] >= 'a' && str[i] <= 'z'){
			str[i] -= 32;
		}

		if(str[i] == '#'){str[i] = '\0';break;}
	}
	//将字符串小写字母转换为大写字母

	printf("\n");
	//循环输出
	for(int k = 0; k < 10; k++){
		printf("%c",str[k]);
	}
	printf("\n");
}