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Pointer and Function in C with Examples

In C, pointers can also be used to pass function arguments and return values. When passing an argument to a function by reference, a pointer to the variable is passed instead of the variable itself. This allows the function to modify the original variable.

For example:

#include<stdio.h>
void increment(int *);
int main() 
{
    int a = 5;
    increment(&a);
    printf("%d", a); // output: 6
    return 0;
}
void increment(int *x)
{
    (*x)++;
}

In this example, the function "increment" takes a pointer to an integer as an argument and increments the value at that memory location. The & operator is used to pass the address of the variable "a" to the function.

Functions can also return a pointer to a variable.

For example:

#include<stdio.h.
int* get_largest(int *,int);
int main()
{
    int numbers[] = {1, 2, 3, 4, 5};
    int* largest = get_largest(numbers, 5);
    printf("%d", *largest); // output: 5
    return 0;
}

int* get_largest(int* arr, int size) 
{
    int* largest = arr;
    for (int i = 1; i < size; i++)
    {
        if (*(arr+i) > *largest)
        {
            largest = arr+i;
        }
    }
    return largest;
}

In this example, the function "get_largest" takes an array of integers and its size as arguments and returns a pointer to the largest element in the array.


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