String Length – C Program

C program to find the Length of String

The total number of characters in a string is called as length of that string.

There are two ways of finding the length of a string:

1. By counting the individual characters of string without using built in library function.
2. Using strlen() function – it is a built in library function.

Example 1: Program to find the length of string without using Library function

Let us write a c program to count the characters of a string without using strlen() function. It is easy to find the length of string using while loop.

Description:

s – input string. It is an array.
c – variable to count the characters.
‘\0’ – NULL character. It marks the end of string.

Algorithm to find the length of string:

STEP 1: START
STEP 2: SET the value of count
              count  = 0
STEP 3: READ the input string whose length is to be counted
              READ s
STEP 4: REPEAT until end of string is not reached
             LOOP character != NULL
             INCREMENT the character count
               count  = count + 1
STEP 5: PRINT the length of string
              PRINT “count”
 STEP 6: END

Program to find the length of string with out using built in function:

#include<stdio.h>
#include<conio.h>
int main()
{
  char s[1000];
  int count = 0;
  printf("Input a string:\n");
  gets(s);
  while (s[count] != '\0')
    count++;
  printf("Length of the string: %d\n", count);
  getch();
  return 0;
}

Output 1:

Input a string:
icantutorials
Length of the string: 13

Output 2:

Input a string:
Learning
Length of the string: 8

Example 2: Program to find the length of string using strlen() function:

• strlen() is a built in library function which is present inside the header file string.h
• The strlen() function returns the length of the given string.
• It doesn’t count null character ‘\0’.

#include <stdio.h>
#include <string.h>
#include<conio.h>
int main()
{
  char s[100];
  int count;
  printf("Enter a string:\n");
  gets(s);
  count = strlen(s);
  printf("Length of the string = %d\n", count);
  getch();
  return 0;
}

Output:

Enter a string:
success
Length of the string = 7

QUIZ:

1] strlen() function is present in header file.

1. stdio.h
2. conio.h
3. string.h
4. math.h

2] NULL character is represented by

1. \n
2. \0
3. \t
4. \r