Score calculation
- C course
- Intermediate
- Lesson 45/116
- 6 min
Learn correct count with the score calculation function.
Score calculation
The fourth lesson defines the print_percentage function. This function computes the score as a percentage and prints it. Percentage shows the success rate clearly.
Signature: void print_percentage(int score, int count). Body: int pct = score * 100 / count; printf("Yüzde: %d%%\n", pct);. Here %% prints a single %. The computation does score * 100 first, then divides by count; this order matters because integer division of score / count * 100 may give the wrong result. The previous lesson's solution is in the starting code.
Integer division
In C, integer division discards the fractional part. This makes the order of operations matter when computing percentages. The right order: multiply first, then divide.
Example: 2 * 100 / 2 = 100 (correct). But 2 / 2 * 100 = 100 also works. The issue shows with small values: 1 / 2 * 100 = 0 * 100 = 0 (wrong, should be 50). Whereas 1 * 100 / 2 = 100 / 2 = 50 (correct). So score * 100 / count is the safe order. Integer division needs care; if you need a float, use a (float) cast.
Practice Write the print_percentage function
Write void print_percentage(int score, int count). In the body compute int pct = score * 100 / count; and print with printf("Yüzde: %d%%\n", pct);. In main, call print_percentage(score, count); (score and count come from previous lessons).
Starter code
#include <stdio.h>
#include <string.h>
struct Question {
char text[64];
int correct;
};
void add_question(struct Question *q, int *count, const char *text, int correct) {
strcpy(q[*count].text, text);
q[*count].correct = correct;
(*count)++;
}
int run_quiz(struct Question *q, int count) {
int answers[3] = {0, 1, 2};
int score = 0;
for (int i = 0; i < count; i++) {
printf("Soru %d: %s\n", i + 1, q[i].text);
if (answers[i] == q[i].correct) {
score++;
}
}
return score;
}
// Write the print_percentage function (score and count)
// Print as "Yüzde: X%"
// In main call print_percentage
int main(void) {
struct Question questions[10];
int count = 0;
add_question(questions, &count, "Başkent?", 0);
add_question(questions, &count, "2+2?", 1);
printf("%d soru eklendi\n", count);
int score = run_quiz(questions, count);
printf("Skor: %d\n", score);
return 0;
}Sample solution
#include <stdio.h>
#include <string.h>
struct Question {
char text[64];
int correct;
};
void add_question(struct Question *q, int *count, const char *text, int correct) {
strcpy(q[*count].text, text);
q[*count].correct = correct;
(*count)++;
}
int run_quiz(struct Question *q, int count) {
int answers[3] = {0, 1, 2};
int score = 0;
for (int i = 0; i < count; i++) {
printf("Soru %d: %s\n", i + 1, q[i].text);
if (answers[i] == q[i].correct) {
score++;
}
}
return score;
}
void print_percentage(int score, int count) {
int pct = score * 100 / count;
printf("Yüzde: %d%%\n", pct);
}
int main(void) {
struct Question questions[10];
int count = 0;
add_question(questions, &count, "Başkent?", 0);
add_question(questions, &count, "2+2?", 1);
printf("%d soru eklendi\n", count);
int score = run_quiz(questions, count);
printf("Skor: %d\n", score);
print_percentage(score, count);
return 0;
}Expected output
2 soru eklendi Soru 1: Başkent? Soru 2: 2+2? Skor: 2 Yüzde: 100%
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Match percentage parts
| Term | Meaning |
|---|---|
score * 100 / count |
Percentage calc |
%d%% |
Percent format |
printf("Yüzde:") |
Output |
void print_percentage |
Function signature |
2 Result of 2 * 100 / 2?
- 0
- 50
- 100 Correct answer
- 200
Explanation: 2*100=200, 200/2=100. Integer division gives the right result.
3 Complete the percentage calc
int pct = score ____ / count;int pct = score * 100 / count;Explanation: score * 100 multiplies first, then division gives the right result.