Find length of string

In this example, we will find the length of string

#include <iostream>
#include <string.h>

using namespace std;

int main(){
    string str = "OceanLabz";
    
    //By Function
    //Length of string using size() methode 
    cout<< str.size() <<endl;

    //Length of string using length methode 
    cout<< str.length() <<endl;


    //By logic
    
    //1
    int i=0;
    while(str[i])
        i++;
    cout<< i << endl;

    //2
    for( i = 0; str[i]; i++);
    cout<< i << endl;

    return 0;
}

Output:

9
9
9
9

Explanation:

Step1: String Declaration

string str = "OceanLabz";

Here, a string str is declared and initialized with the value "OceanLabz". The length of this string is 9 characters.

Step2: Finding the Length Using Built-in Methods

Using size() Method

cout<< str.size() << endl;

• The size() method returns the number of characters in the string str.
• In this case, it will return 9, since "OceanLabz" has 9 characters.

Using length() Method

cout<< str.length() << endl;

• The length() method is equivalent to size() and returns the number of characters in the string str.
• It also returns 9.

Both size() and length() are functionally identical for C++ std::string objects, providing the length of the string.

Step3: Finding the Length Using Logic (Manual Counting)

Logic 1: Using while Loop

int i = 0;
while(str[i])
    i++;
cout<< i << endl;

• This loop manually counts the characters in the string.
• str[i] accesses each character in the string. The loop runs until it encounters the null terminator (\0), which signifies the end of the string.
• Each time the loop iterates, i is incremented, effectively counting the characters.
• After the loop finishes, i holds the length of the string, which is printed as 9.

Logic 2: Using for Loop

for(i = 0; str[i]; i++);
cout<< i << endl;

• This for loop does the same thing as the while loop but in a more compact form.
• The loop runs as long as str[i] is not the null terminator (\0), incrementing i at each step.
• Once the loop ends, i will hold the length of the string, which is printed as 9.