函数式编程 - 按引用传递 (Call By Reference)

在按引用传递中，将会更改原始值，因为我们传递了参数的引用地址。实际参数和形式参数共享相同的地址空间，因此函数内部的任何值更改都会在函数内部和外部体现出来。

C++ 中的按引用传递

以下程序演示了在 C++ 中按引用传递如何工作的 −

#include <iostream> 
using namespace std; 

void swap(int *a, int *b) {    
   int temp; 
   temp = *a; 
   *a = *b; 
   *b = temp; 
   cout<<"\n"<<"value of a inside the function: "<<*a; 
   cout<<"\n"<<"value of b inside the function: "<<*b; 
}  
int main() {     
   int a = 50, b = 75;   
   cout<<"\n"<<"value of a before sending to function: "<<a; 
   cout<<"\n"<<"value of b before sending to function: "<<b; 
   swap(&a, &b);  // passing value to function 
   cout<<"\n"<<"value of a after sending to function: "<<a; 
   cout<<"\n"<<"value of b after sending to function: "<<b; 
   return 0;   
}

它将生成以下输出 −

value of a before sending to function:  50 
value of b before sending to function:  75 
value of a inside the function:  75 
value of b inside the function: 50 
value of a after sending to function:  75 
value of b after sending to function:  50 

Python 中的按引用传递

def swap(a,b): 
   t = a; 
   a = b; 
   b = t; 
   print "value of a inside the function: :",a 
   print "value of b inside the function: ",b 
   return(a,b) 
    
# Now we can call swap function 
a = 50 
b =75 
print "value of a before sending to function: ",a 
print "value of b before sending to function: ",b 
x = swap(a,b) 
print "value of a after sending to function: ", x[0] 
print "value of b after sending to function: ",x[1] 

它将生成以下输出 −

value of a before sending to function:  50 
value of b before sending to function:  75 
value of a inside the function:  75 
value of b inside the function:  50 
value of a after sending to function:  75 
value of b after sending to function:  50