How to filter out extra spaces in the C language?

In C language, the following methods can be used to filter out extra spaces:

1. Traverse the string using pointers and save the filtered results in a new string.

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

void filterSpaces(char *str) {
    char *filtered = str; // 用于保存过滤后的字符串
    int isSpace = 0; // 标记当前字符是否为空格

    // 遍历字符串
    while (*str) {
        if (isspace(*str)) {
            // 如果当前字符为空格
            if (!isSpace) {
                // 如果前一个字符不是空格，则将当前字符保存到filtered中
                *filtered++ = *str;
                isSpace = 1; // 设置isSpace为1，表示当前字符为空格
            }
        } else {
            // 如果当前字符不是空格，则将当前字符保存到filtered中
            *filtered++ = *str;
            isSpace = 0; // 设置isSpace为0，表示当前字符不是空格
        }
        str++;
    }

    // 在filtered的末尾添加字符串结束符'\0'
    *filtered = '\0';
}

int main() {
    char str[100];
    printf("请输入字符串：");
    scanf("%[^\n]", str);

    filterSpaces(str);

    printf("过滤后的字符串为：%s\n", str);

    return 0;
}

1. By using two pointers, one pointing to the original string and one to the filtered string, skip characters that do not meet the requirements.

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

void filterSpaces(char *str) {
    char *filtered = str; // 用于保存过滤后的字符串

    // 遍历字符串
    while (*str) {
        if (!isspace(*str)) {
            // 如果当前字符不是空格，则将当前字符保存到filtered中
            *filtered++ = *str;
        }
        str++;
    }

    // 在filtered的末尾添加字符串结束符'\0'
    *filtered = '\0';
}

int main() {
    char str[100];
    printf("请输入字符串：");
    scanf("%[^\n]", str);

    filterSpaces(str);

    printf("过滤后的字符串为：%s\n", str);

    return 0;
}

Both of these methods can filter out extra spaces, with the output being the filtered string.