 When you write a program that uses a loop to do some task repeatedly, you need some way to figure out whether to continue the loop or to end it. Here's a flow chart for a loop that does a task 10 times. We know how to set a counter and add one to it. The question is how to do a test for the condition that tells us whether to continue the loop or not. To test a condition, you need to use one of these relational operators. You use a less than symbol to test whether one value is less than another or not. When C was invented, graphic terminals were nearly non-existent and extremely expensive, so there was no way to directly type a less than or equal to symbol, which is why we have to type it this way in C. Greater than and greater than or equal follow the same pattern. To test if two values are equal, we use two equal signs in a row. This is important. A single equal sign means assignment. A double equal sign asks the question, are these two values the same? Finally, we have this symbol for not equal to. All of these operators return zero for false and one for true. Here's a program that shows several conditional tests. Again, all of these will return a value of zero if the condition is false, or one if the condition is true. And here's the output of the program.