C program to print reverse of a string without using inbuilt functions

PROGRAM:

#include <stdio.h>
int length(char[]);
void rev(char []);
int main()
{
    char str[50];
    printf("Enter a string\n");
    scanf("%s",str);
    rev(str);
    return 0;
}
int length(char str[])
{
    int i=0,count=0;
    while(str[i]!='\0')
    {
        ++count;
        ++i;
    }
    return count;
}

void rev(char str[])
{
    int i=0;
    char str2[50];
    while(str[i]!='\0')
    {
        str2[length(str)-1-i]=str[i];
        ++i;
    }
    str2[i]='\0';
    printf("Reversed string is %s",str2);
}

OUTPUT:

Enter a string
cprogram
Reversed string is margorpc