Given a string str, the task is to convert the given string into the number without using any inbuilt function.
Examples:
Input: str = “985632”
Output: 985632
Explanation:
Given input is in string form and returned output is in integer form.Input: str = “123”
Output: 123
Explanation:
Given input is in string form and returned output is in integer form.
Approach: The idea is to use the ASCII value of the digits from 0 to 9 start from 48 – 57.
Therefore, to change the numeric character to an integer subtract 48 from the ASCII value of the character will given the corresponding digit for the given character.
Below is the implementation of the above approach:
C++
// C++ program for tha above approach #include <iostream> using namespace std; // Function to convert string to // integer without using functions void convert(string s) { // Initialize a variable int num = 0; int n = s.length(); // Iterate till length of the string for (int i = 0; i < n; i++) // Subtract 48 from the current digit num = num * 10 + (int(s[i]) - 48); // Print the answer cout << num; } // Driver Code int main() { // Given string of number char s[] = "123"; // Function Call convert(s); return 0; } |
C
// C program for the above approach #include <stdio.h> #include <string.h> // Function to convert string to // integer without using functions void convert(char s[]) { // Initialize a variable int num = 0; int n = strlen(s); // Iterate till length of the string for (int i = 0; i < n; i++) // Subtract 48 from the current digit num = num * 10 + (s[i] - 48); // Print the answer printf("%d", num); } // Driver Code int main() { // Given string of number char s[] = "123"; // Function Call convert(s); return 0; } |
Java
// Java program for the above approach class GFG{ // Function to convert string to // integer without using functions public static void convert(String s) { // Initialize a variable int num = 0; int n = s.length(); // Iterate till length of the string for(int i = 0; i < n; i++) // Subtract 48 from the current digit num = num * 10 + ((int)s.charAt(i) - 48); // Print the answer System.out.print(num); } // Driver code public static void main(String[] args) { // Given string of number String s = "123"; // Function Call convert(s); } } // This code is contributed by divyeshrabadiya07 |
Python3
# Python3 program for the above approach # Function to convert string to # integer without using functions def convert(s): # Initialize a variable num = 0 n = len(s) # Iterate till length of the string for i in s: # Subtract 48 from the current digit num = num * 10 + (ord(i) - 48) # Print the answer print(num) # Driver code if __name__ == '__main__': # Given string of number s = "123" # Function Call convert(s) # This code is contributed by Shivam Singh |
C#
// C# program for the above approach using System; class GFG{ // Function to convert string to // integer without using functions public static void convert(string s) { // Initialize a variable int num = 0; int n = s.Length; // Iterate till length of the string for(int i = 0; i < n; i++) // Subtract 48 from the current digit num = num * 10 + ((int)s[i] - 48); // Print the answer Console.Write(num); } // Driver codepublic static void Main(string[] args){ // Given string of number string s = "123"; // Function call convert(s); }} // This code is contributed by rock_cool |
123
Time Complexity: O(N), where N is the length of the given string.
Auxiliary Space: O(1)
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