给定一个字符串str ,任务是在不使用任何内置函数的情况下将给定的字符串转换为数字。
例子:
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.
方法:想法是使用从0 到 9从48 – 57开始的数字的 ASCII 值。
因此,从字符的ASCII值的数字字符改变为整数减法器48将给出对于给定字符的相应数字。
下面是上述方法的实现:
C++
// C++ program for tha above approach
#include
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
#include
// 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 code
public static void Main(string[] args)
{
// Given string of number
string s = "123";
// Function call
convert(s);
}
}
// This code is contributed by rock_cool
输出:
123
时间复杂度: O(N) ,其中 N 是给定字符串的长度。
辅助空间: O(1)
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