我想实现输入一串字符然后提取其中的数字，请问代码是出了什么问题吗(关键词-#include)

Question

我想实现输入一串字符然后提取其中的数字，但是为什么运行后是这个结果，请问代码是出了什么问题吗？

#include <stdio.h>
int main()
{
    char ch;
    int n;
    printf("Please input an integer number:");
    ch = getchar();
    while (ch < '0' || ch > '9')
    {
        ch = getchar();
    }
    n = 0;
    while (ch >= '0' && ch <= '9')
    {
        n = n * 10 + (ch - '0');
        ch = getchar();
    }
    printf("%d", n);
    return 0;
}

Answer 1

#include <stdio.h>

int main() {
    char ch;
    int n = 0;
    int foundNumber = 0;
    int firstNumber = 1;

    printf("Please enter a string: ");

    while ((ch = getchar())!= '\n') {
        if (ch >= '0' && ch <= '9') {
            foundNumber = 1;
            n = n * 10 + (ch - '0');
        } else {
            if (n > 0) {
                if (!firstNumber) {
                    printf(" ");
                }
                printf("%d", n);
                firstNumber = 0;
                n = 0;
            }
        }
    }

    if (n > 0) {
        if (!firstNumber) {
            printf(" ");
        }
        printf("%d", n);
    }

    if (!foundNumber) {
        printf("No number found in the input.");
    }

    return 0;
}