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Encrypt a string by repeating i-th character i times
Introduction
A C++ string is a fixed sequence of alphanumeric characters. It is a continuous stream of occurring characters, which may be digits, characters or even special symbols. Every string is characterized by a definite length. The positions by which the characters are accessed begin with 0.
Strings can contain unique or repeated characters concatenated together. They can be subjected to various manipulations and concatenation operations.
In this article, we are going to develop a code that takes as input a string, and displays the encrypted string, wherein the first character is repeated 1 time, the second character is repeated 2 times. This procedure is repeated until the length of the string. Let us look at the following example to understand the topic better −
Sample Example
Example 1 − str − “g@m$”
Output − g@@mmm$$$$
For instance, the following example string, contains special characters also, which are repeated according to the position of the character in the string.
In this article, we will create a solution to compute the number of times the character at a particular position should be repeated. The extracted character is then appended to the output string generated, until the count is exhausted.
Syntax
str.length()
length()
The size of the string can be captured by the length() method, which is used to return the alphanumeric characters and the special symbols contained within the string
Algorithm
An input string str is accepted as input
A counter, cnt is maintained to store the number of times each character should be repeated. It is initialized with the value of 0.
The length of the string is computed using the length() method and stored in a variable named len
Each time the character at ith position is extracted.
The counter, cnt is computed by incrementing the position i by 1.
A decrementing loop initialized with the counter value is performed to append the extracted character to the output string, res
Each time the counter value is decremented
After performing the required number of iterations with the character, the pointer is shifted on to the next character
Example
The following C++ code snippet is used to create an encrypted string from the given input sample string −
//including the required libraries
#include <bits/stdc++.h>
using namespace std;
// Function to return the encrypted string
string encrypt(string str) {
//counter to store the number of times a character is repeated
int cnt = 0;
//storing the encrypted string
string res = "";
//computing the length of the string
int len = str.length();
for(int i =0 ; i<len ; ) {
//getting the count of the number of times the character will be repeated
cnt = i + 1;
//repeating the current character
while (cnt){
//extracting the character at ith index
char ch = str[i];
//adding the character to output string
res += ch;
//decrementing the count
cnt--;
}
i++;
}
cout << "Encrypted string "<< res;
}
int main() {
//taking a input string
string str = "heyy";
cout << "Input string "<< str <<"\n";;
//creating an encrypted string
encrypt(str);
return 0;
}
Output
Input string heyy Encrypted string heeyyyyyyy
Conclusion
The character positions in a C++ string start from by default the 0th index. A string is a dynamic length storage structure where the characters can be appended easily any number of times. String concatenation can easily be performed in C++ using the + operator. During each character addition the length of the string increases by 1.
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