std::string::erase in C++ - GeeksforGeeks

28 Mar, 2022
The function erases a part of the string content, shortening the length of the string. The characters affected depend on the member function version used: Return value : erase() returns *this. 
Time Complexity : O(n) , n=length of string
Syntax 1: Erases all characters in a string
Syntax 1: Erases all characters in a string
string& string ::erase ()
CPP
// CPP code to illustrate// erase() function #include <iostream>#include <string>using namespace std; // Function to demo erase()void eraseDemo(string str){    // Deletes all characters    str.erase();     cout << "After erase() : ";    cout << str;} // Driver codeint main(){    string str("Hello World!");     cout << "Before erase() : ";    cout << str << endl;    eraseDemo(str);     return 0;}
Output: 
Before erase() : Hello World!
After erase() : 
 
 2. Syntax 2: Erases all characters after position ‘pos’ 
string& string ::erase (size_type pos)
- Throw out_of_range if idx > size().
CPP
// CPP code to illustrate working of// erase(idx) #include <iostream>#include <string>using namespace std; // Function to demo erasevoid eraseDemo(string str){    // Deletes all characters except first one    str.erase(1);     cout << "After erase(idx) : ";    cout << str;} // Driver codeint main(){    string str("Hello World!");     cout << "Before erase(idx) : ";    cout << str << endl;    eraseDemo(str);     return 0;}
Output: 
Before erase(idx) : Hello World!
After erase(idx) : H
3. Syntax 3: Erases at most, len characters of *this, starting at index idx. 
string& string ::erase (size_type idx, size_type len )
- If len is missing, all remaining characters are removed.
- Throw out_of_range if idx > size().
CPP
// CPP code to illustrate// erase(size_type idx, size_type len )#include <iostream>#include <string>using namespace std; // Function to demo erasevoid eraseDemo(string str){    // Deletes 4 characters from index number 1    str.erase(1, 4);     cout << "After erase : ";    cout << str;} // Driver codeint main(){    string str("Hello World!");     cout << "Before erase : ";    cout << str << endl;    eraseDemo(str);     return 0;}
Output: 
Before erase : Hello World!
After erase : H World!
4. Syntax 4: Erase the single character at iterator position pos. 
string& string ::erase (iterator pos)
- Return the first character after the last character removed
- If no such character is remaining then, returns 
  string::end() i.e. position after the last character.
CPP
// CPP code to illustrate// erase(iterator pos) #include <iostream>#include <string>using namespace std; // Function to demo erasevoid eraseDemo(string str){    // Deletes character at position 4    str.erase(str.begin() + 4);     cout << "After erase : ";    cout << str;} // Driver codeint main(){    string str("Hello World!");     cout << "Before erase : ";    cout << str << endl;    eraseDemo(str);     return 0;}
Output: 
Before erase : Hello World!
After erase : Hell World!
5. Syntax 5: Erase characters from iterator pos. to another iterator pos. 
string& string ::erase (iterator beg, iterator end )
- Erases all characters of the range [ beg, end)
- Returns end i.e. the first character after the
  last character removed.
- If no such character is remaining then, returns 
  string::end() i.e. position after the last character
CPP
// CPP code to illustrate// erase(iterator pos, iterator end) #include <iostream>#include <string>using namespace std; // Function to demo erasevoid eraseDemo(string str){    // Deletes all characters between 0th index and    // str.end() - 6    str.erase(str.begin() + 0, str.end() - 6);     cout << "After erase : ";    cout << str;} // Driver codeint main(){    string str("Hello World!");     cout << "Before erase : ";    cout << str << endl;    eraseDemo(str);     return 0;}
Output: 
Before erase : Hello World!
After erase : World!
Related Article : std::string::clear This article is contributed by Sakshi Tiwari. If you like GeeksforGeeks (We know you do!) and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
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