a c program to check palindrome

#include<stdio.h>
#include<conio.h>
#include<math.h>
#include<string.h>
int main ()
{char str1[100];
char str2[100];
printf("entr a srting   \n");
gets(str1);

strcpy(str2,str1);
strrev(str2);
if(strcmp(str1,str2)==0)
printf("it is a palindrome");
else
printf("not a palindrome");





getch();
return 0;
}

C program code to convert decimal to hexadecimal

#include<stdio.h>
#include<conio.h>
#include<math.h>
void dtoh(int d);
main()
{

int d;
printf("Enter a no. in decimal system:- ");
scanf("%d",&d);
dtoh(d);

getch();
}

void dtoh(int d)
{
int b,c=0,a[5],i=0;
b=d;
while (b>15)
{
a[i]=b%16;
b=b/16;
i++;
c++;
}
a[i]=b;
printf("Its hexadecimal equivalent is ");
for (i=c;i>=0;--i)
{
if (a[i]==10)
printf("A");
else if (a[i]==11)
printf("B");
else if (a[i]==12)
printf("C");
else if (a[i]==13)
printf("D");
else if (a[i]==14)
printf("E");
else if (a[i]==15)
printf("F");
else
printf("%d",a[i]);
}
return o;
}