basic_string c_str function in C++ STL (original) (raw)

Last Updated : 7 Feb, 2023

The basic_string::c_str() is a built-in function in C++ which returns a pointer to an array that contains a null-terminated sequence of characters representing the current value of the basic_string object. This array includes the same sequence of characters that make up the value of the basic_string object plus an additional terminating null-character at the end.

Syntax:

const CharT* c_str() const

Parameter: The function does not accept any parameter.

Return Value : The function returns a constant Null terminated pointer to the character array storage of the string.

Below is the implementation of the above function:

Program 1:

CPP `

// C++ code for illustration of // basic_string::c_str function #include <bits/stdc++.h> #include using namespace std;

int main() { // declare a example string string s1 = "GeeksForGeeks";

// check if the size of the string is same as the
// size of character pointer given by c_str
if (s1.size() == strlen(s1.c_str())) {
    cout << "s1.size is equal to strlen(s1.c_str()) " << endl;
}
else {
    cout << "s1.size is not equal to strlen(s1.c_str())" << endl;
}

// print the string
printf("%s \n", s1.c_str());

}

`

Output

s1.size is equal to strlen(s1.c_str()) GeeksForGeeks

Program 2:

CPP `

// C++ code for illustration of // basic_string::c_str function #include <bits/stdc++.h> #include using namespace std;

int main() { // declare a example string string s1 = "Aditya";

// print the characters of the string
for (int i = 0; i < s1.length(); i++) {
    cout << "The " << i + 1 << "th character of string " << s1
        << " is " << s1.c_str()[i] << endl;
}

}

`

Output

The 1th character of string Aditya is A The 2th character of string Aditya is d The 3th character of string Aditya is i The 4th character of string Aditya is t The 5th character of string Aditya is y The 6th character of string Aditya is a

Program 3:

C++ `

// CPP program to copy the string // using std:🧵:c_str() method #include <bits/stdc++.h>

// Function to copy the string const char* copyString(std::string s) { const char* s2;

// std:🧵:c_str() method
s2 = s.c_str();

return s2;

}

// Driver Code int main() { std::string s1 = "GeeksforGeeks"; std::string s2;

// Function Call
s2 = copyString(s1);
std::cout << s2;
return 0;

}

// This code is contributed by Susobhan Akhuli

`