In programming, each character of a string has an assigned index, starting from zero to length – 1. Index 0 starts from the first character and the last character's index is length – 1. Special characters and white spaces also have an assigned index.
For example: If we consider the string "Hello World";
Here, the length will be 11 and the indexing will be from 0 to 10.
In the following algorithm, we will be using the same logic to reverse the given string.
The algorithm starts by taking the string to be reversed as input from the user. After that, the length of the string is calculated and stored in a variable, say 'length'. To store the reversed string, we are initializing a variable 'rev' as an empty string.
We will reverse the string by accessing the string from its last character. To do so, we are starting a loop with initial value i = length – 1. In this loop, we are reversing the string, one character at a time by performing: rev = rev + character at position 'i'. Here, the '+'' operator performs the concatenation of the characters of the string in reverse order. After that, the value of 'i' is decremented by 1. This loop runs until i >= 0. Once this loop ends, we have the reversed string in the variable rev.