我的代码要求我从.txt文件输入名称，如果名称有效，我可以登录。
当程序启动时，应该向用户提供三个选项; 按0退出 按1获取作者信息 按2登录 选择0退出程序 选择1将打印您的姓名和学生ID 选择3会提示用户输入用户名和密码。 然后，您应该打开文件“passwords”，看看用户是否有权使用程序*
到目前为止我已经这样做了。成功登录后，我可以按选项2添加新学生。到目前为止我已经这样做了。现在我对选项4犯了一个错误。选项4要求我为学生输入一个成绩。点击选项4后，它会询问我的成绩，每当我输入成绩时，程序就会崩溃。我不确定我的错误是什么。
//This is my code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* Constants used in the application */
const char * PASSWORD_FILE = "passwords.txt";
const int MAX_STUDENTS = 1000;
const int MAX_GRADES = 100;
const int MAX_CHARS = 25;
//Function to print Author Info
void printAuthorInfo();
//Function to display initial Menu and Get the User's Selection
int showMainMenu();
//Function to Login to the System
int login();
//member menu
int memberMenu();
//Enter GPA for current Student
void enterGPA(char ids[1000][25], float grades[1000][100], int[], int);
//Display student records to stdout
void print(char[1000][25], char[1000][25], char[1000][25], float[1000][100],
int[], int);
//Save Records to File
void save(char[1000][25], char[1000][25], char[1000][25], float[1000][100],
int[], int);
//Load Records from File
void load(char fn[1000][25], char ln[1000][25], char ids[1000][25], float
grades[1000][100], int counts[], int num);
int main()
{
int loggedIn = 0;
int choice, subChoice;
char firstNames[1000][25];
char lastNames[1000][25];
char ids[1000][25];
float grades[1000][100];
int numGrades[1000];
char fn[25];
char ln[25];
int numStudents = 0;
//Top Level Loop
do {
//display menu and get the user's selection
choice = showMainMenu();
if (choice == 0)
{
printf("Thank you for using our Application! GoodBy!");
}
else if (choice == 1)
{
printAuthorInfo();
}
else if (choice == 2)
{
loggedIn = login();
if (loggedIn == 1)
{
printf("Welcome! You are now Logged In\n");
//Interact with the user
do
{
subChoice = memberMenu();
if (subChoice == 1)
{
printAuthorInfo();
}
else if (subChoice == 2)
{
printf("Enter First Name: ");
scanf("%s", firstNames[numStudents]);
printf("Enter Last Name: ");
scanf("%s", lastNames[numStudents]);
printf("Enter Student ID: ");
scanf("%s", ids[numStudents]);
numStudents++;
printf("Student Has been added to System");
}
else if (subChoice == 3)
{
enterGPA(ids, grades, numGrades, numStudents);
}
else if (subChoice == 4)
{
print(firstNames, lastNames, ids, grades, numGrades,
numStudents);
}
else if (subChoice == 5)
{
void save(firstNames, lastNames, ids, grades, counts,
numStudents);
}
else if (subChoice == 6)
{
load(firstNames, lastNames, ids, grades, numGrades,
&numStudents);
}
else if (subChoice == 7)
{
printf("\nYou are logged Out Now");
}
printf("\n");
} while (subChoice != 7);
}
else
{
printf("Login Failed - Try again");
}
}
printf("\n\n");
} while (choice != 0);
system("pause");
return 0;
}
void printAuthorInfo()
{
printf("Author Information\n");
printf("Author Name: %s\n", "myinfo ");
printf("Student ID: %s\n", "12345");
}
int showMainMenu()
{
//User Selection
int choice;
do
{
//Display menu
printf("Press 0 to exit\n");
printf("Press 1 for Author Info\n");
printf("Press 2 for Login\n");
printf("Enter choice? ");
//Read the selection
scanf("%d", &choice);
printf("\n");
} while (choice < 0 || choice > 2);
//Return selection
return choice;
}
int login()
{
//Get User's username and password
char username[30];
char password[30];
char usernameInFile[30];
char passwordInFile[30];
int valid = 0;
//Prompt and get Username
printf("Enter Username: ");
scanf("%s", username);
//Prompt and get Password
printf("Enter Password: ");
scanf("%s", password);
//Open the input file
FILE * fptr = fopen(PASSWORD_FILE, "r");
while (fscanf(fptr, "%s %s", usernameInFile, passwordInFile) == 2)
{
if (strcmp(username, usernameInFile) == 0 && strcmp(password,
passwordInFile) == 0)
{
valid = 1;
}
}
fclose(fptr);
return valid;
}
int memberMenu()
{
int choice = 0;
do
{
printf("Press 1 for author info\n");
printf("Press 2 to Enter new student\n");
printf("Press 3 to enter grade for existing student\n");
printf("Press 4 to print student records\n");
printf("Press 5 to save student records\n");
printf("Press 6 to load student records\n");
printf("Press 7 to logout\nEnter Selection? ");
scanf("%d", &choice);
printf("\n");
} while (choice < 1 || choice > 7);
return choice;
}
void print(char fn[1000][25], char ln[1000][25], char ids[1000][25], float
grades[1000][100], int counts[], int num)
{
int i, j;
float sum, avg;
sum = 0;
avg = 0;
printf("%-15s %-15s %-10s %-8s %-8s\n", "First Name",
"Last Name", "Std ID", "GPA", "Grades");
for (i = 0; i < num; i++)
{
printf("%-15s %-15s %-10s", fn[i], ln[i], ids[i]);
for (j = 0; j < counts[i]; j++)
{
sum += grades[i][j];
}
avg = sum / counts[i];
sum = 0;
printf("%-8.2f", avg);
for (j = 0; j < counts[i]; j++)
{
printf("%-6.2f", grades[i]);
}
printf("\n");
}
}
void save(char fn[1000][25], char ln[1000][25], char ids[1000][25], float
grades[1000][100], int counts[], int num)
{
int i, j;
float sum, avg;
char fname[100];
sum = 0;
avg = 0;
//Get file name
printf("Enter Output File Name: ");
scanf("%s", fname);
FILE * fptr = fopen(fname, "w");
fprintf(fptr, "%d\n", num);
for (i = 0; i < num; i++)
{
fprintf(fptr, "%s %s %s %d ", fn[i], ln[i], ids[i], counts[i]);
for (j = 0; j < counts[i]; j++)
{
fprintf(fptr, "%.2f ", grades[i]);
}
fprintf(fptr, "\n");
}
fclose(fptr);
}
void load(char fn[1000][25], char ln[1000][25], char ids[1000][25], float
grades[1000][100], int counts[], int * num)
{
char fname[100];
int cur = *num;
int i, j, n, numStudents = 0;
float grade;
//prompt and get input file
printf("Enter Input File Name: ");
scanf("%s", fname);
//open file to read
FILE * fptr = fopen(fname, "r");
fscanf(fptr, "%d", &numStudents);
for (i = 0; i < numStudents && cur < 1000; i++)
{
fscanf(fptr, "%s %s %s %d", fn[cur], ln[cur], ids[cur], &n);
for (j = 0; j < n && counts[i] < 100; j++)
{
fscanf(fptr, "%f", &grade);
grades[i][counts[i]] = grade;
counts[i] += 1;
}
cur += 1;
}
*num = cur;
fclose(fptr);
}
void enterGPA(char ids[1000][25], float grades[1000][100], int counts[], int
num)
{
char id[25];
int i, idx;
float gpa;
idx = -1;
printf("Enter Student ID: ");
scanf("%s", id);
//find student
for (i = 0; i < num && idx == -1; i++)
{
if (strcmp(id, ids[i]) == 0)
{
idx = i;
}
}
if (idx >= 0)
{
printf("Enter Grade: ");
scanf("%f", &gpa);
grades[idx][counts[idx]] = gpa;
counts[idx] += 1;
}
else
{
printf("NO Such Student Exist In The System");
}
}
答案 0 :(得分：1)
我可以立即看到两个问题。
printf("%-6.2f", grades[i];
由于grades是2D数组，因此它应该是
printf("%-6.2f", grades[i][j]
load的函数声明不正确。它应该是
void load(char fn[1000][25], char ln[1000][25], char ids[1000][25],
float grades[1000][100], int counts[], int *num);
（注意int* num）
可能还有其他问题，但如果没有输入文本文件，很难找到。