Common Mistakes in C++ Level 1 Programming (47C++): Understanding the for Loop. Level 1 questions include multiple-choice, true/false, and programming questions, all of which will involve the for loop. The total score is approximately 50 points. If the for loop is misunderstood, it is basically hopeless.
Why do many students misunderstand the for loop?
for LoopSteps of loop execution: First, initialize the loop control variable; Second, evaluate the loop termination condition. If the result is true, proceed to the third step; if false, the loop terminates and exits; Third, execute the loop body; Fourth, increment the loop control variable and return to the second step. |
Where are the common mistakes? Typically, exam questions will ask what the value of the variable is at the end of the loop.
For example:
Will i be greater than 5 here? When is i output?
First round: i=1 Output 1#
Second round: i=2 Output 2#
Third round: i=3 break; At this point, the for loop ends. No further execution of i++
So the answer is A
Will i be greater than 11 here? Many candidates see the condition in the for loop, i<11, and think that i will also be 11 after execution. But here i+=3.
So the possible values for i are: 1, 4, 7, 10, 13 (not satisfying the condition, the loop ends) thus i finally equals 13.
The for loop is used in scenarios where the number of iterations is known, looping under specific conditions. i stops when the first condition is not met.
For example, for (i=0; i<10; i++) after execution, i=11;
Sometimes, the for loop can have no conditions and no variable increment. For example:
int i=0; for(;i<=100;) // Loop condition { sum+=i; // Loop body i++; // Loop correction condition } Do you understand?
Have you learned it?