Write a C function to reverse a string. Write a program in C which prints the smallest divisor of an integer, for example, the smallest divisor of 77 is 7.

WBUT / MAKAUT MCA 2012

Reverse a string

We can reverse a string in two different ways- (i) Using another string (ii) without using second string. As per question here no need to write the main() function.

• Using another string: Read the given string from the end and copy the characters in another string variable. After coping the entire variable a null (‘\0’) character place at last position of the new string to terminate it.

  		void reverse_string()
  		{
  			char str[40],strrev[40];
  			int len,i,j=0;
  			printf("Enter a String");
  			gets(str);
  			len=strlen(str);
  			for(i=len-1;i>=0;i--)
  			{
  				strrev[j++]=str[i];
  			}
  			strrev[j]='\0';
  			puts(strrev);
  			getch();
  		}
  		


• Without using second string: This method is much more accurate than above. Because according to the question, we are instructed to reverse the existing string, but in the first method, the original string is not changed.

  In this method, we interchange the first characters with the last character, after then, interchange the second character with the second last character and so on up to reach at the mid of the given string.

  			void reverse_string()
  			{
  				char str[40],temp;
  				int len,i;
  				printf("Enter a String");
  				gets(str);
  				len=strlen(str);
  				for(i=0;i<len;i++)
  				{
  					if(if<=(len/2))
  					{
  						temp=str[i];
  						str[i]=str[len-1-i];
  						str[len-1-i]=temp;
  					}
  				}
  				puts(str);
  				getch();
  			}
  			

Smallest Divisor

Here we start the divide the given number by 2. If it is not divided by 2 then divide it by 3 and so on. By which no the given number is divisible is known as the smallest divisor of the given number. As per question here we must write the main() function.

void main()
{
	int no,sd=2;
	printf("Enter a number");
	scanf("%d",&no);
	while(no%sd!=0)
	{
		sd++;
	}
	printf("The smallest divisor of %d is %d",no,sd);
	getch();
}