C++ Program to Find Length of String

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Here, you will learn how to find and print the length of any given string by the user at run-time, in C++ language. The program is created with the help of these approaches:

  • Find length of string without using any library or built-in function like strlen()
  • using strlen() function
  • using Pointer

Find Length of String without strlen() Function

To find the length of a string in C++ programming, you have to ask from user to enter the string first. And then find its length as shown in the program given below.

This program finds the length of a string using user-based code. That is, this program does not use library function or built-in function, strlen().

// C++ Find Length of String without strlen() Function #include<iostream> #include<stdio.h> using namespace std; int main() { char str[200]; int len=0, i=0; cout<<"Enter the String: "; gets(str); while(str[i]) { len++; i++; } cout<<"\nLength = "<<len; cout<<endl; return 0; }
Code language: C++ (cpp)

Output

Enter the String: Welcome to Techarge
Lenght=19

Find Length of String using strlen() Function

Here is another C++ program that also finds and prints length of string entered by user. The only difference with previous program is, this program uses a built-in or library function of C++ named strlen().

The function, strlen() takes string as its argument and returns its length. This function is defined in string.h header file.

// C++ Find Length of String using strlen() Function #include<iostream> #include<stdio.h> #include<string.h> using namespace std; int main() { char str[200]; int len=0; cout<<"Enter the String: "; gets(str); len = strlen(str); cout<<"\nLength = "<<len; cout<<endl; return 0; }
Code language: C++ (cpp)

Output

Enter the String: Welcome to Techarge
Lenght=19

Find Length of String using Pointer

Now let’s create the same purpose program, that is to find length of a string, but using pointer. The address of first character of string gets initialized to pointer type variable say ptr and using this variable, the length of string gets calculated.

Note – The & is called as address of operator. Whereas as the * is called as value at operator. The ptr++ (char pointer type variable) moves to next character’s address

// C++ Find Length of String using Pointer #include<iostream> #include<stdio.h> using namespace std; int main() { char str[200], *ptr; int len=0; cout<<"Enter the String: "; gets(str); ptr = &str[0]; while(*ptr) { len++; ptr++; } cout<<"\nLength = "<<len; cout<<endl; return 0; }
Code language: C++ (cpp)

Output

Enter the String: Welcome to Techarge
Lenght=19

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