std::string::replace , std::string::replace_if in C++
replace()
It replaces each element in the range [first, last) that is equal to oldValue with newValue. The function uses operator == to compare the individual elements to old_value.
template <class ForwardIterator, class T>
void replace (ForwardIterator first, ForwardIterator last,
const T& old_value, const T& new_value);
first, last : the range of elements to process
old_value : the value of elements to replace
new_value : the value to use as replacement
C++
// CPP code to demonstrate replace()#include <iostream>using namespace std;// Function for demonstrationvoid replaceDemo(string s1, string s2, string s3, string s4){ // Replaces 7 characters from 0th index by s2 s1.replace(0, 7, s2); cout << s1 << endl; // Replaces 3 characters from 0th index with "Hello" s4.replace(0, 3, "Hello "); cout << s4 << endl; // Replaces 5 characters from 6th index of s4 with // 5 characters from 0th of s3 s4.replace(6, 5, s3, 0, 5); cout << s4 << endl; // Replaces 5 characters from 6th index of s4 with // 6 characters from string "to all" s4.replace(6, 5, "to all", 6); cout << s4 << endl; // Replaces 1 character from 12th index of s4 with // 3 copies of '!' s4.replace(12, 1, 3, '!'); cout << s4 << endl;}// Driver codeint main(){ string s1 = "Example of replace"; string s2 = "Demonstration"; string s3 = "GeeksforGeeks"; string s4 = "HeyWorld !"; replaceDemo(s1, s2, s3, s4); return 0;} |
Output:
Demonstration of replace Hello World ! Hello Geeks ! Hello to all ! Hello to all!!!!
replace_if
replace_if() replaces each element in the range [first, last) for which the unary predicate i.e. op(elem) yields true with newValue.
template <class ForwardIterator, class UnaryPredicate, class T>
void replace_if (ForwardIterator first, ForwardIterator last,
UnaryPredicate pred, const T& new_value );
Unary predicate are just functions that take a single parameter
and return a Boolean value. It is used to check whether an
element fits the criterion
C++
// CPP code to demonstrate replace_if()#include <iostream>#include <vector>#include <algorithm> // Header file for replace_ifusing namespace std;// Function to check if character is vowel or notbool IsVowel(char ch){ return (ch == 'A' || ch == 'E' || ch == 'I' || ch == 'O' || ch == 'U');}// Function to replace all vowels with 'V'void replace_ifDemo(vector<char>&v){ replace_if(v.begin(), v.end(), IsVowel, 'V');}// Function to print content of vectorvoid print(vector<char>&v){ int len = v.size(); for (int i = 0; i < len; i++) cout << v[i] << " "; cout << endl;}// Driver codeint main(){ vector<char> v; for (int i = 0; i <= 6; i++) v.push_back('A' + i); cout << "Before replace_if " <<": "; print(v); replace_ifDemo(v); cout << "After replace_if " << ": "; print(v); return 0;} |
Output:
Before replace_if : A B C D E F G After replace_if : V B C D V F G
Related Article : std::string::replace_copy(), std::string::replace_copy_if
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