Home
C/C++ Coding Exercisse – How to Implement ToLowerCase Function?
Tags:, ,

C/C++ Coding Exercisse – How to Implement ToLowerCase Function?

August 10, 2018 No Comments c / c++, learn to code, string

Implement function ToLowerCase() that has a string parameter str, and returns the same string in lowercase.

Allocate a string and assign input string to it. Change uppercase letters to lowercase by adding 32 to its ASCII code.

1
2
3
4
5
6
7
8
9
10
11
12

class Solution {
public:
    string toLowerCase(string str) {
        auto r = str;
        for (auto i = 0; i < str.length(); ++ i) {
            if (r[i] >= 'A' && r[i] <= 'Z') {
                r[i] += 32;
            } 
        }
        return r;
    }
};
class Solution {
public:
    string toLowerCase(string str) {
        auto r = str;
        for (auto i = 0; i < str.length(); ++ i) {
            if (r[i] >= 'A' && r[i] <= 'Z') {
                r[i] += 32;
            } 
        }
        return r;
    }
};

Alternatively, you can modify the string inplace without allocating a new string, and return it.

1
2
3
4
5
6
7
8
9
10
11

class Solution {
public:
    string toLowerCase(string str) {
        for (auto i = 0; i < str.length(); ++ i) {
            if (str[i] >= 'A' && str[i] <= 'Z') {
                str[i] += 32;
            } 
        }
        return str;
    }
};
class Solution {
public:
    string toLowerCase(string str) {
        for (auto i = 0; i < str.length(); ++ i) {
            if (str[i] >= 'A' && str[i] <= 'Z') {
                str[i] += 32;
            } 
        }
        return str;
    }
};

The C solution:

1
2
3
4
5
6
7
8
9
10

char* toLowerCase(char* str) {
    char* s = str;
    while (*str != '\0') { // not the end of the string
        if (*str >= 'A' && *str <= 'Z') {
            *str = *str + 32;
        }
        ++ str;
    }
    return s;
}
char* toLowerCase(char* str) {
    char* s = str;
    while (*str != '\0') { // not the end of the string
        if (*str >= 'A' && *str <= 'Z') {
            *str = *str + 32;
        }
        ++ str;
    }
    return s;
}

The string is an array of characters, which can be accessed by moving the pointer.

Using std::transform in C++

We can use the std::transform in C++ to transform a vector to another using a customize transform function, which we will use the std::tolower function to convert to a lower character.

1
2
3
4
5
6
7
8
9

class Solution {
public:
    string toLowerCase(string str) {
        std::transform(begin(str), end(str), begin(str), [](auto &ch) { 
            return std::tolower(ch); 
        });
        return str;
    }
};
class Solution {
public:
    string toLowerCase(string str) {
        std::transform(begin(str), end(str), begin(str), [](auto &ch) { 
            return std::tolower(ch); 
        });
        return str;
    }
};

–EOF (The Ultimate Computing & Technology Blog) —

GD Star Rating
loading...
287 words
Last Post: C++ Coding Exercise - Find All Duplicates in an Array
Next Post: C++ Coding Exercise - How to Merge Two Binary Trees?

The Permanent URL is: C/C++ Coding Exercisse – How to Implement ToLowerCase Function?

Related posts:

  1. Pointer Arithmetic in Delphi Delphi is based on Object Pascal, which is a great programming language. Delphi is also...
  2. How to Evaluate Reverse Polish Notation using Stack? Polish notation/expression is also known as ‘prefix notation’ where the numbers are preceded by its...
  3. Interview Coding Exercise – Nested String (Python) Nested String A string S consisting of N characters is considered to be properly nested...
  4. Providing an IsUnicodeVersion API in Your Delphi Project I have recently migrated my project from Delphi 2007 to Delphi XE8 (and Seattle). It...
  5. Algorithm to Compute the Fraction to Recurring Decimal of the Two Integer Division Given two integers representing the numerator and denominator of a fraction, return the fraction in...
  6. Design a Logger Rate Limiter in C++/Java Design a logger system that receive stream of messages along with its timestamps, each message...
  7. How to Construct Minimum Spanning Tree using Kruskal or Breadth First Search Algorithm? There are N cities numbered from 1 to N. You are given connections, where each...
  8. The Contiguous Binary Array with Equal Numbers of Ones and Zeros Given a binary array, find the maximum length of a contiguous subarray with equal number...

Leave a Reply