qsort() – Utility Function

qsort() – Utility Function

How is Utility function “qsort()” used in C++?
How to Sort the Elements of the Array?

Explanation

qsort() is a Utility Function that is used to quick sort an array. The “size”, number of elements (“num”) is specified in this function.

Syntax:

void qsort(void *buf, size_t num, size_t size,
int (*compare) (const void *, const void *));

In the above syntax “compare” is used to compare the elements with a keys of an array. This function returns “0” if both arguments are equal, if “arg1” is less than “arg2” the a negative value is returned. If “arg1” is greater then a positive value is returned by the function. The following is the syntax of this function.

Syntax:

int func_name(const void *arg1, const void *arg2);

Example :

#include
#include
#include
int main ()
{
int i;
char arr[3][20] = {“2”, “1”, “3” };
qsort(arr,3, 20, (int(*) (const void*,
const void*))strcmp);
printf(“The sorted arrayn”);
for (i=0; i<3; ++i)
printf (“%sn”, arr[i]);
return 0;
}

Result :

The sorted array
1
2
3

In the above example qsort() function is used to sort the array in descending order.





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