C++ Strings

Introduction 

Before knowing about string functions, we have to know about string. In C++ string is an object of a string class representing the sequence of characters. String functions are nothing, just functions that are used to perform operations on a string. To use these string functions in C++, you need to add a library named <string> in your code at the top, which gives you various string functions like strlen, strcmp, strcat, swap, strcpy, and many more. 

Fibonacci Series in C++

Common String Functions in C++:

• strlen(str1): It is used to find the length of a string.
• strcpy(str1,str2): It is used to copy the content of a string into another.
• strcat(str1,str2): It is used to append two strings.
• strcmp(str1,str2): this string function returns negative value if str1 is less than str2, 0 if str1 is equal to str2, and positive value if str1 is greater than str2.
• substr(starting index, from that index how many characters you want): It is used to take the substring from the given string.
   

Now we will discuss how to use the string function in C++ with the help of some examples.

String length example in C++

Here is a simple example of finding the string length using strlen(),size() and length() functions.

Code

// C++ Program to demonstrate the working of strlen(), size() and length()
#include<iostream>
#include<string.h>  // for string class
using namespace std;
int main()
{
    // Initializing the string
    char str1[]="codingninjas";
    string str2="string functions are very useful";
    cout<<"The length of the first string using strlen(): ";
    cout<<strlen(str1)<<endl;
    cout<<"The length of the second string using size(): ";
    cout<<str2.size()<<endl;
    cout<<"The length of the second string using length(): ";
    cout<<str2.length()<<endl;
    return 0;
}

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Output 

The length of the first string using strlen(): 12
The length of the second string using size(): 32
The length of the second string using length(): 32

String Copy Example in C++

Here is a simple example of copying the string using strcpy() function.

Code 

// Simple C++ Program to demonstrate the working of strcpy()
#include<iostream>
#include<string.h>  // for string class
using namespace std;
int main()
{
    // Initializing the string
    char str1[50]="Coding Ninjas";
    char str2[50];
    strcpy(str2,str1);
    cout<<"The value of the first string is: ";
    cout<<str1<<endl;
    cout<<"The value of the second string is: ";
    cout<<str2<<endl;
    return 0;
}

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Output 

The value of the first string is: Coding Ninjas
The value of the second string is: Coding Ninjas

String Concat Example in C++

Here is a simple example of the string concatenation using Strcat() function

Code 

// C++ Program to demonstrate the working of strcat()
#include<iostream>
#include<string.h>  // for string class
using namespace std;
int main()
{
    // Initializing the string
    char str1[]="Coding";
    char str2[]=" Ninjas";
    strcat(str1,str2);
    cout<<"The value of the first string is: ";
    cout<<str1<<endl;
    cout<<"The value of the second string is:";
    cout<<str2<<endl;
    return 0;
}

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Output

The value of the first string is: Coding Ninjas
The value of the second string is: Ninjas

Try and compile with online c++ compiler.

String Compare Example in C++

Here is a simple example of the string comparison using strcmp() function.

Code

// C++ Program to demonstrate the working of strcmp()
#include<iostream>
#include<string.h>  // for string class
using namespace std;
int main()
{
    // Initializing the string
    char str1[]="Coding";
    char str2[]="Coding";
    int res=strcmp(str1,str2);
    cout<<res<<endl;
    return 0;
}

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Output

0

In the above code, the res is 0. This means that both the strings are the same.