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Beginner to Advanced Computing and Logic Building

Case Conversion in Strings

Explore how to create functions that convert strings to lowercase and uppercase using ASCII values in C++. Understand different approaches including a special lowercase conversion that preserves the first letter of each word. Practice through challenges that enhance your string manipulation skills.

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String conversion to lowercase

Let’s make a strLower() function in which we need to convert uppercase alphabets to lowercase by adding the ASCII value. For example, if the ASCII value of A is 65, simply add 32 to convert it into lowercase. If you don’t remember the ASCII value, you can add the following in the alphabet:

alphabet+'a'-'A'
C++
#include <iostream>
#include <string.h>
using namespace std;
void strLower(char S[ ])
{
    for(int si=0; S[si]!='\0'; si++)
    {
        if(S[si]>='A' && S[si]<='Z')
        {
            S[si]+=32;   // the ascii value of 'a' 97 i.e. 65(ascii value of 'A')+32 and so on
        }
    }
}
int main()
{
    char S[ ] = "THIS is A WORLD OF C++";
    cout << "Before lowering: "<<S<<endl;
    strLower(S);
    cout << "After  lowering: "<<S<<endl;
    return 0;
}

Here are two challenges for you.

Exercise 1: String conversion to uppercase

Write the strUpper() function solution.

Sample input

This is A World of C++

Sample output

THIS IS A WORLD OF C++

#include <iostream>
#include <string.h>
using namespace std;
void strUpper(char S[ ])
{
    //write your code here
}
int main()
{
    char S[ ] = "This is A WORLD of C++";
    cout << "Before strUpper function:"<<S<<endl;
    strUpper(S);
    cout << "After strUpper function: "<<S<<endl;
    return 0;
}
The strUpper() function

Exercise 2: Special to lowercase conversion

Write the strLowerSpecial() function, which lowers the case of all the characters but not the start of the word.

Sample input

THIS IS PAKISTAN

Sample output

This Is Pakistan 

#include <iostream>
#include <cstring>
using namespace std;
void strLowerSpecial(char S[ ])
{
    //write your code here
}
int main()
{
    char S[ ] = "THIS IS PAKISTAN";
    cout << "Before lowering: "<<S<<endl;
    strLowerSpecial(S);
    cout << "After  lowering: "<<S<<endl;
    return 0;
}
The strLowerSpecial() function