Q.Write a C program to accept two floating point numbers and complete their ratio. If the ratio is greater than zero then it should exchange the contents of the numbers. The textbook presents this worked program, transcribed exactly as printed (including its printed errors):

#include<stdio.h>  
void main()  
{  
float a, b, ratio, temp;  
printf("Enter a and b\n");  
scanf("%f%f", &a, &b);  
ratio=a/b;  
printf("Ratio =%f\n", ratio);  
if (ratio>0);  
{           /* block begins */  
temp=a;  
a=b;  
b=temp  
}  
/*End of if*/  
printf("a=%f, b=%f\n", a,b);  
}  
/*End of main()*/  

Sample output printed in the textbook:

Enter the value of a and b  
19.0  
36.0  
Ratio = 0.527777  
a = 36.000000, b = 19.000000  

By default a C program runs its statements one after another, but decision (conditional) control statements let it choose between alternative paths depending on a condition. They are the basis of all decision-making programs.

• if statement - executes a block only when its condition is true; if the condition is false the block is skipped.

  if (condition)
      statement;
  

• if-else statement - provides two alternatives: one block runs when the condition is true, the other when it is false.

  if (condition)
      statement1;
  else
      statement2;
  

• Nested-if / else-if ladder - an if (or if-else) placed inside another, used to test several conditions in turn. This is how a program picks the largest of three numbers, or grades a value into ranges such as short, average and tall. …