C PROGRAMMING PROGRAM • STRINGS

Compare Two Strings Without strcmp()

Learn how to compare two strings without strcmp() using a clear C program.

BeginnerStringsCharacter arraysLoops

PROBLEM UNDERSTANDING

Input and expected output

Sample input
apple
apricot
Sample output
First string comes before second

COMPLETE C PROGRAM

Complete C implementation

compare-strings-without-strcmp.c
Open in compiler
#include <stdio.h>
#include <string.h>

int main(void)
{
    char first[200], second[200];
    int index = 0;

    fgets(first, sizeof first, stdin);
    fgets(second, sizeof second, stdin);
    first[strcspn(first, "\n")] = '\0';
    second[strcspn(second, "\n")] = '\0';
    while (first[index] != '\0' && first[index] == second[index]) index++;
    if (first[index] == second[index]) printf("Strings are equal\n");
    else if ((unsigned char) first[index] < (unsigned char) second[index]) printf("First string comes before second\n");
    else printf("First string comes after second\n");
    return 0;
}

GUIDED CODE TOUR • NOT LIVE EXECUTION

Study the program line by line

Use the real compiler button above to run and debug with different inputs.

CURRENT STEP

Select Start to walk through the important lines.

SELECTED LINE

No line selected

EXPECTED OUTPUT FOR THE SAMPLE

First string comes before second
0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

  1. Read the required input values.
  2. Advance through equal characters and compare the first differing character.
  3. Display the computed result.

Advance through equal characters and compare the first differing character.

EFFICIENCY

Time and space complexity

Time complexity

O(n)

Auxiliary space

O(1)

DEBUGGING CHECKLIST

Common mistakes

Check this

Use the correct format specifier for every variable.

Check this

Initialize variables before using their values.

Check this

Check braces, semicolons and input order carefully.

Try it yourself

Practice: Run the program with the sample input, predict its output, and then test one boundary case of your own.