c - 如何删除C程序中的重复输出？

Question

我创建了一个从用户输入中获取字符的程序。它将字母转换为大写并将其显示给最终用户。

但是，我收到了一个输出问题，我得到了双倍的“请输入小写字符:”和下面的额外一行。我不太确定是什么原因造成的，但这是我目前的程序:

#include <stdio.h>
#include <stdbool.h>
#include <ctype.h>

// Converts lowercase letter to uppercase

int main()
{
    bool continue_program = true;

    printf("Program Running \n");
    int lower, upper;
    while (continue_program){
        printf("Please enter a character in lower case:");
        printf("\n");
        int lower = getchar();
        if(lower=='q' || lower=='Q'){
            printf("Goodbye \n");
            break;
        } else {
            upper = toupper(lower);
            putchar(upper);
            printf("\n");
        }
    }
    return 0;
}

输出示例:

./a.out
Program Running 
Please enter a character in lower case:
a
A
Please enter a character in lower case:


Please enter a character in lower case:
b
B
Please enter a character in lower case:


Please enter a character in lower case:
p
P
Please enter a character in lower case:


Please enter a character in lower case:
Q
Goodbye 

Answer 1

只要改变这个:

int lower, upper;

到:

char lower, upper;

还有这个:

int lower = getchar();

到:

scanf(" %c", &lower);
     //^ Space which 'eats' remaning '\n' in the buffer