Question

How to convert binary string to int number in C++

Answer 1

#include <iostream> 

int main() 
{ 
    std::string s = "1001"; 
    
    int i = std::stoi(s, nullptr, 2);
    
    std::cout << i;
    
    return 0; 
} 



/*
run:

9

*/

 

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Answer 2

#include <iostream> 

int strbin2int(std::string s) {
    int n = 0, base = 1, len = s.length(); 
    
    for (int i = len - 1; i >= 0; i--) { 
        if (s[i] == '1') 
            n += base; 
        base = base * 2; 
    } 
  
    return n; 
}

int main() 
{ 
    std::string s = "1001"; 
    
    int i = strbin2int(s);
    
    std::cout << i;
    
    return 0; 
} 



/*
run:

9

*/

 

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