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Basic
Switch Case
Goto
Operators
if Statement
Nested if
While Loop
For Loop
Patterns
Array
2D Array
String Function Example
Pointers
Recursion Function
Structure
Excersises
Others



C Program to Find Length of the Longest Word in a Sentence


Write a C program to find length of the longest word in a given sentence.

  • Reads a full sentence from the user character-by-character until a newline is encountered.
  • Scans through the sentence to detect the start and length of each word separated by spaces.
  • Tracks the longest word by updating maxLen and its starting index whenever a longer word is found.
  • Copies the longest word into a new string and prints it along with its length.
Example : pgm.c 
#include <stdio.h>

int main() {
    char str[200];
    char longest[100];
    int i = 0, start = 0, maxLen = 0, len = 0;

    printf("Enter a sentence: ");
    while ((str[i] = getchar()) != '\n') {
        i++;
    }
    str[i] = '\0';

    i = 0;
    while (str[i] != '\0') {
        if (str[i] != ' ') {
            int wordStart = i;
            int wordLen = 0;

            while (str[i] != ' ' && str[i] != '\0') {
                wordLen++;
                i++;
            }

            if (wordLen > maxLen) {
                maxLen = wordLen;
                start = wordStart;
            }
        } else {
            i++;
        }
    }

    // Copy the longest word into a new string
    for (i = 0; i < maxLen; i++) {
        longest[i] = str[start + i];
    }
    longest[i] = '\0';

    printf("Longest word: %s\n", longest);
    printf("Length: %d\n", maxLen);

    return 0;
}

Output :

Enter a sentence: C language is powerful and expressive
Longest word: expressive
Length: 10