C program to find the length of a string

Given a string str. The task is to find the length of the string.

Examples: 

Input: str = "Geeks"
Output: Length of Str is : 5

Input: str = "GeeksforGeeks"
Output: Length of Str is : 13

In the below program, to find the length of the string str, first the string is taken as input from the user using scanf in , and then the length of Str is calculated using and using method .
Below is the C program to find the length of the string.
Example 1: Using loop to calculate the length of string.

C

// C program to find the length of string
#include <stdio.h>
#include <string.h>

int main()
{
    char Str[1000];
    int i;

    printf("Enter the String: ");
    scanf("%s", Str);

    for (i = 0; Str[i] != '\0'; ++i);

    printf("Length of Str is %d", i);

    return 0;
}

Output:

Enter the String: Geeks
Length of Str is 5

Time Complexity: O(N)

Auxiliary Space: O(1)

Example 2: Using strlen() to find the length of the string.

C

// C program to find the length of
// string using strlen function
#include <stdio.h>
#include <string.h>

int main()
{
    char Str[1000];
    int i;

    printf("Enter the String: ");
    scanf("%s", Str);

    printf("Length of Str is %ld", strlen(Str));

    return 0;
}

Output:

Enter the String: Geeks
Length of Str is 5

Time Complexity: O(1)

Auxiliary Space: O(1)