std::string::clear in C++

Last Updated : 17 Jul, 2026

The std::string::clear() function is a member of the std::string class defined in the <string> header. It removes the contents of a string without destroying the string object itself.

  • Makes the string empty by removing all stored characters.
  • Commonly used before storing new data in the same string object.
CPP 
#include <iostream>
#include <string>
using namespace std;

// Function to demo clear()
void clearDemo(string str)
{
    // Deletes all characters in string
    str.clear();

    cout << "After clear : ";
    cout << str;
}

// Driver code
int main()
{
    string str("Hello World!");

    cout << "Before clear : ";
    cout << str << endl;
    clearDemo(str);

    return 0;
}

Output
Before clear : Hello World!
After clear :

Explanation: The clear() function removes every character from the string, leaving it empty.

Syntax

string_name.clear();

string_name is the string whose contents are to be removed.

Additional Examples

The following examples demonstrate different uses of std::string::clear().

1. Clearing a String Before Reusing It

C++ 
#include <iostream>
#include <string>
using namespace std;

int main() {

    string str = "Programming";

    str.clear();

    str += "GeeksforGeeks";

    cout << str;

    return 0;
}

Output
GeeksforGeeks

Explanation: The original contents are removed using clear(), and the same string object is reused to store new text.

2. Checking Whether a String Becomes Empty

C++ 
#include <iostream>
#include <string>
using namespace std;

int main() {

    string str = "Hello";

    str.clear();

    if (str.empty())
        cout << "String is empty";

    return 0;
}

Output
String is empty

Explanation: After calling clear(), the empty() function confirms that the string contains no characters.

Applications

std::string::clear() is commonly used in the following situations:

  • Resetting a string before storing new data.
  • Reusing the same string object multiple times.
  • Clearing temporary string buffers.
  • Removing all contents without creating another string.

Best Practices

Follow these practices while using std::string::clear():

  • Use clear() when the entire string needs to be emptied.
  • Prefer reusing an existing string instead of creating a new one repeatedly.
  • Use empty() to verify whether the string contains any characters after clearing.
  • Use erase() instead when only a portion of the string needs to be removed.
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