Convert string to Char Array in C++

In this article, we are going to see how to convert string to char array in C++.

[toc]

String vs character array in C++

In C, we used string as character array. String used to be a collection of characters terminated by a NULL character.
char str[]=”Java2Blog”
Here,

If it was merely a character array then, the NULL character would have been missing.
Another way we can say,

It is the case for C. But in C++, we have additional advantage to use ‘string’ as a datatype. So there’s differences between string and character array in C++. We can list few of those out here.
Character array is collection of data type ‘char’. ‘string’ is itself a data type.
We can use data type operations (‘+’, ‘==’ etc.) on ‘string’, but not on character array.
To find the length, we can use .length() for ‘ string’. But for character array, there will be predefined size or have to compute the length using for loop like following:

int length=0;
for(int i=0;str[i]!=’\0’;i++){
    length++;
}
cout<<”string(character array  length: ”<

Convert string to char array in C++

String is used as a data type in C++. Here goes some quick review about string in C++.

#include   
using namespace std; 

int main(){
    //declare string
    string str1,str2,finalstring;
    cout<<"Enter first string\n";
    //input strings as data type
    cin>>str1;
    cout<<"Enter second string\n";
    cin>>str2;
    //operating on string like other datatype
    finalstring=str1+str2;
    //output string
    cout<<"Concatenated string: "<

Output:

Using for loop

To convert a C++ string into char array the general procedure is:

• Input the string
• Define a char array with some predefined size or with size = string length
• Iterate through the string and build the char array
• Output the char array

Following is the code & output for the above procedure.

#include   
using namespace std; 

int main(){
    //declare string
    string str;
    cout<<"Enter first string\n";
    //input strings as data type
    cin>>str;

    //size=string length
    int size=str.length()+1; //plus 1 to adjust the null character of c string

    //define character array

    char arr[size];

    //iterate through the string and build the character array

    for(int i=0;i< str.length();i++){

        arr[i]=str[i];
    }
    arr[size-1]='\0';
    cout<<"converted to character array\n";
    //print the character array

    for(int i=0;i

Output:

Notice that 10th character in the char array is blank in output, because it’s a null character.

Using c_str() and strcpy()

c_str() is a library function which converts C++ string data type to a C strng. Then we can copy it to character array using strcpy() which a cstring library function.

#include   //it includes all the libraries
using namespace std; 

int main(){
    //declare string
    string str;
    //input str
    cout<<"Input string:\n";
    cin>>str;

    int size=str.length()+1; //plus 1 to adjust the null character of c string

    char arr[size];
    //strcpy to copy the converted c string in character array 
    strcpy(arr,str.c_str());
    cout<<"Converted to char array\n";
    cout<

Output:

Using copy() function of library

Another way is to use copy() function of CPP library

#include    //it includes all libraries
using namespace std; 

int main(){
    //declare string
    string str;
    //input str
    cout<<"Input string:\n";
    cin>>str;

    int size=str.length()+1; //plus 1 to adjust the null character of c string

    //initialize array
    char arr[size];
    //copy() to copy the entire c++ string in the character array 
    copy(str.begin(),str.end(),arr);
    //add null character
    arr[size-1]='\0';
    cout<<"Converted to char array\n";
    cout<

Output:

Using copy() function of library

We can also use copy() function of library like the following way:

#include   //it includes all the libraries
using namespace std; 

int main(){
    //declare string
    string str;
    //input str
    cout<<"Input string:\n";
    cin>>str;

    int size=str.length()+1; //plus 1 to adjust the null character of c string

    //initialize array
    char arr[size];
    //string.copy() to copy the entire c++ string in the character array 
    str.copy(arr,str.length());
    //add null character
    arr[size-1]='\0';
    cout<<"Converted to char array\n";
    cout<

That’s all about how to convert string to char array in C++.