c语言写一个函数,输人一行字符,将此字符串中最长的单词输出。

好的，我可以回答这个问题。以下是一个用C语言写的函数，它可以输入一行字符串，并输出其中最长的单词：

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

void findLongestWord(char sentence[]) {
    int len = strlen(sentence);
    int longestLength = 0, currentLength = 0;
    char longestWord[100], currentWord[100];
    int wordStartIndex = 0, wordEndIndex = 0;

    for (int i = 0; i <= len; i++) {
        if (sentence[i] == ' ' || sentence[i] == '\0') {
            currentLength = wordEndIndex - wordStartIndex;
            strncpy(currentWord, &sentence[wordStartIndex], currentLength);
            currentWord[currentLength] = '\0';

            if (currentLength > longestLength) {
                longestLength = currentLength;
                strncpy(longestWord, currentWord, longestLength);
                longestWord[longestLength] = '\0';
            }

            wordStartIndex = i + 1;
        } else {
            wordEndIndex = i;
        }
    }

    printf("最长的单词是：%s\n", longestWord);
}

使用以上代码，你可以输入一行字符串，并找到其中最长的单词。希望对你有所帮助！