有人可以帮助如何在多个函数中声明 int 吗？ C

Question

这是我的代码:

#include <stdio.h>



double CalculateFinalScore(int assignment[], int midterm[], int finalExam[], double scoreSum[], char gradeAchieved[]) 
{
    int i = 0;

    for (i = 0; i < NUM_SCORES; ++i) 
    {
        scoreSum[i] = (assignment[i] * 0.2) + (midterm[i] * 0.3) + (finalExam[i] * 0.5);
    }
}

char grade(int assignment[], int midterm[], int finalExam[], double scoreSum[], char gradeAchieved[]){
    char A = 'A';
    char B = 'B';
    char C = 'C';
    char D = 'D';
    char E = 'E';

    int j = 0;

    for (j = 0; j < NUM_SCORES; ++j){

    if ((CalculateFinalScore(assignment[], midterm[], finalExam[], scoreSum[], gradeAchieved[]) >= 85 ) {
        gradeAchieved[j] = A;
    }
    else if ((CalculateFinalScore(assignment[], midterm[], finalExam[], scoreSum[], gradeAchieved[]) >= 75) && (CalculateFinalScore(assignment[], midterm[], finalExam[], scoreSum[], gradeAchieved[]) < 85)  ){
        gradeAchieved[j] = B;
    }
    else if ((CalculateFinalScore(assignment[], midterm[], finalExam[], scoreSum[], gradeAchieved[]) >= 60) && (CalculateFinalScore(assignment[], midterm[], finalExam[], scoreSum[], gradeAchieved[]) < 75)  ){
        gradeAchieved[j] = C;
    }
    else if ((CalculateFinalScore(assignment[], midterm[], finalExam[], scoreSum[], gradeAchieved[]) >= 45) && (CalculateFinalScore(assignment[], midterm[], finalExam[], scoreSum[], gradeAchieved[]) < 60)  ){
        gradeAchieved[j] = D;
    } 
    else if ((CalculateFinalScore(assignment[], midterm[], finalExam[], scoreSum[], gradeAchieved[]) >= 0) && (CalculateFinalScore(assignment[], midterm[], finalExam[], scoreSum[], gradeAchieved[]) < 45)  ){
        gradeAchieved[j] = E;
    }
    } 
}

int main(void) 
{
    int NUM_SCORES;
    char finalGrade[NUM_SCORES];
    double testScores[NUM_SCORES]; 
    int i = 0;
    int x[NUM_SCORES];
    int y[NUM_SCORES];
    int z[NUM_SCORES];

    // Prompt user to enter test scores
    printf("Input number of students: ");
    scanf("%d", &NUM_SCORES);


    for (i = 0; i < NUM_SCORES; ++i) 
    {
        printf("Input student %d assignment score: ", (i+1));
        scanf("%d", &(x[i]));
        printf("Input student %d midterm score: ", (i+1));
        scanf("%d", &(y[i]));
        printf("Input student %d final exam score: ", (i+1));
        scanf("%d", &(z[i]));
        printf("\n");

    }

    printf("\n");
    // Call function to calculate final score
    CalculateFinalScore(x, y, z, testScores, finalGrade);

    for (i = 0; i < NUM_SCORES; ++i) 
    {
        printf("Final student %d test score: ", (i+1));
        printf("%lf\n", testScores[i]);

        printf("Final student %d test score: ", (i+1));
        printf("%lf\n", finalGrade[i]);
    }

    return 0;
}

}

所以基本上，与我的代码不同，其中 NUM_SCORES 已经用 4 确定。相反，我想输入 NUM_SCORES 值，这样我就可以轻松确定它的值，但每次我这样做时，总会出现一个错误，即我的 NUM_SCORES 未声明。哦，我也遇到了这些错误

main.c: In function ‘CalculateFinalScore’:
main.c:9:21: error: ‘NUM_SCORES’ undeclared (first use in this function)
     for (i = 0; i < NUM_SCORES; ++i)
                     ^~~~~~~~~~
main.c:9:21: note: each undeclared identifier is reported only once for each function it appears in
main.c: In function ‘grade’:
main.c:24:21: error: ‘NUM_SCORES’ undeclared (first use in this function)
     for (j = 0; j < NUM_SCORES; ++j){
                     ^~~~~~~~~~
main.c:26:41: error: expected expression before ‘]’ token
     if ((CalculateFinalScore(assignment[], midterm[], finalExam[], scoreSum[], gradeAchieved[]) >= 85 ) {
                                         ^
main.c:26:105: error: expected ‘)’ before ‘{’ token
     if ((CalculateFinalScore(assignment[], midterm[], finalExam[], scoreSum[], gradeAchieved[]) >= 85 ) {
                                                                                                         ^
main.c:41:5: error: expected expression before ‘}’ token
     }
     ^
main.c: In function ‘main’:
main.c:81:19: warning: format ‘%lf’ expects argument of type ‘double’, but argument 2 has type ‘int’ [-Wformat=]
         printf("%lf\n", finalGrade[i]);
                   ^

有人可以帮我解决这个问题吗？

Answer 1

您不能使用变量维度声明数组(就像在您的 main 中一样)。 因此，最简单的方法是假设常量 MAX_SCORES，它始终大于 NUM_SCORES，并使用它声明数组。

为了确保您的 NUM_SCORES 在所有函数中都可见，请使用全局静态变量。

此外，您应该仅通过数组名称将数组作为指针传递给函数，而不使用 [](如在 c# 中；))。

#include <stdio.h>

// define below to maximum value, what you expected
#define MAX_SCORES 255

// declare global variable
static int NUM_SCORES = 0; // this is good practice to initialize global variables

double CalculateFinalScore(int *assignment, int *midterm, int *finalExam, double *scoreSum, char *gradeAchieved) 
{
    // your function body
}

char grade(int *assignment, int *midterm, int *finalExam, double *scoreSum, char *gradeAchieved)
{
    // your function body
}

int main(void) 
{
    // int NUM_SCORES; <- remove this!
    char finalGrade[MAX_SCORES];
    double testScores[MAX_SCORES]; 
    int i = 0;
    int x[MAX_SCORES];
    int y[MAX_SCORES];
    int z[MAX_SCORES];

    // Prompt user to enter test scores
    printf("Input number of students: ");
    scanf("%d", &NUM_SCORES);

    // check NUM_SCORES is less than MAX_SCORES
    if (NUM_SCORES >= MAX_SCORES) {
        printf("\nNumber too big! Should be less than: %d\n", MAX_SCORES);
        return 0;
    }

    // the rest of main() body
}

最后，仅使用大写字母命名变量并不是一个好习惯 - 这种命名是使用 #define 指令定义的常量的“保留”。 如果您想表明它是全局变量，只需在名称开头添加下划线('_')，例如 _numScores。