C51 learning experience, function call by reference and function call by value-EEWORLD

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Call by value creates a copy of the parameter and passes it to the called function. Modifying the copy of the parameter value in the calling function does not affect the original variable value; call by reference allows the calling function to modify the value of the original variable.

C language uses pointer * and indirect reference operator & to simulate call by reference. Arrays will automatically simulate call by reference. Call by reference can modify the parameter variables in the calling function environment in the called function, and call by value protects data.

(1) Call by value

int cubeByValue(int);

main()

{ int num=5,result;

result=cubeByValue(num);

}

int cubeByValue(int n)

{

return n*n*n;

}

(2) Call by reference

int cubeByValue(int *);

main()

{ int num=5,result;

cubeByValue(&num); // pass the address of num to nPtr

printf("%d",num);

}

int cubeByValue(int *nPtr)

{

*nPtr=*nPtr * *nPtr * *nPtr;

}

int array[size];

void modifyarray(int [],int );

void MIDI fyarray(array,size)

{

void swap( int *,int *);

......

}

Note: The function prototype swap can be defined in the calling function midifyarray, as shown above, to ensure that swap can only be called correctly in the calling function m

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