cannot import name 'decimal' from 'decimal'

当出现"cannot import name 'decimal' from 'decimal'"的错误时，通常是因为引用了不存在的模块。根据你提供的引用内容，错误可能是由于你拼写错误导致的。在第一个引用中，你导入了decimal模块并使用了它的Decimal类，但是你拼写了Deciaml而不是Decimal。请检查你的代码并确保正确导入和拼写decimal模块及其类名。

相关问题

there is a file，use c write a System Requirements: A. To make the program as user-friendly as possible, use the following menu to start. 1. Import grades for a course 2. Delete a course 3. Calculate GPA 4. Export file with GPA 5. Quit User will choose the functions using the index number: 1: ask user to import a file from which the grades will be added to students.txt. a) The program should ask the user to input the course name before input the file name. It is assumed that the length of course name is less than 20. b) If the course name inputted by user exists in students.txt, gives user a warning. User can choose to replace the old grades with new or not. If user choose not to replace, go back to main menu. c) If the course name does not exist in students.txt, ask the user to give the file name to import. d) If it is found that a student ID in this imported file cannot be found in the students.txt, do not import and give the warning. Each ID contains 10 digits. It is assumed that each file has been sorted according to ID in ascending order before it is imported. 2: ask user to input the course name to delete. If the course name does not exist in students.txt, gives a warning. 3: the system will calculate GPA for each student in students.txt and put the GPA in the file too. Keep two decimal points in GPA. 4: when user has this choice, the system will display a sub-menu. 1. Sorted in ID (ascending) 2. Sorted in GPA (descending) 3. Back to main menu In this sub-menu, if user chooses 1 or 2, the system will ask user to input a file name to export to. If user chooses 3, system goes back to main menu. 5: Quit the system.

下面是根据您提供的需求编写的C程序代码，实现了系统的功能要求：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_COURSE_NAME_LENGTH 20
#define MAX_STUDENT_ID_LENGTH 11

typedef struct {
    char student_id[MAX_STUDENT_ID_LENGTH];
    char course_name[MAX_COURSE_NAME_LENGTH];
    float grade;
} Student;

void import_grades(Student *students, int *num_students);
void delete_course(Student *students, int *num_students);
void calculate_gpa(Student *students, int num_students);
void export_file(Student *students, int num_students);
void sort_by_id(Student *students, int num_students);
void sort_by_gpa(Student *students, int num_students);

int main() {
    Student students[100];  // 假设最多有100个学生
    int num_students = 0;
  
    int choice;
    do {
        printf("\n=== Main Menu ===\n");
        printf("1. Import grades for a course\n");
        printf("2. Delete a course\n");
        printf("3. Calculate GPA\n");
        printf("4. Export file with GPA\n");
        printf("5. Quit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                import_grades(students, &num_students);
                break;
            case 2:
                delete_course(students, &num_students);
                break;
            case 3:
                calculate_gpa(students, num_students);
                break;
            case 4:
                export_file(students, num_students);
                break;
            case 5:
                printf("Quitting the system...\n");
                break;
            default:
                printf("Invalid choice! Please try again.\n");
        }
    } while (choice != 5);

    return 0;
}

void import_grades(Student *students, int *num_students) {
    char course[MAX_COURSE_NAME_LENGTH];
    char file_name[100];
  
    printf("Enter the course name: ");
    scanf("%s", course);

    // Check if the course already exists
    for (int i = 0; i < *num_students; i++) {
        if (strcmp(students[i].course_name, course) == 0) {
            printf("Warning: Course already exists.\n");
            printf("Do you want to replace the old grades? (y/n): ");
            char replace_choice;
            scanf(" %c", &replace_choice);
            if (replace_choice == 'n' || replace_choice == 'N') {
                return;
            }
        }
    }

    printf("Enter the file name to import: ");
    scanf("%s", file_name);

    FILE *file = fopen(file_name, "r");
    if (file == NULL) {
        printf("Error opening file.\n");
        return;
    }

    char student_id[MAX_STUDENT_ID_LENGTH];
    float grade;
  
    while (fscanf(file, "%s %f", student_id, &grade) == 2) {
        if (strlen(student_id) != MAX_STUDENT_ID_LENGTH - 1) {
            printf("Warning: Invalid student ID.\n");
            continue;
        }

        // Check if student ID already exists
        int existing_student_index = -1;
        for (int i = 0; i < *num_students; i++) {
            if (strcmp(students[i].student_id, student_id) == 0) {
                existing_student_index = i;
                break;
            }
        }

        if (existing_student_index != -1) {
            // Update existing student's grade
            students[existing_student_index].grade = grade;
            strcpy(students[existing_student_index].course_name, course);
        } else {
            // Add new student
            strcpy(students[*num_students].student_id, student_id);
            strcpy(students[*num_students].course_name, course);
            students[*num_students].grade = grade;
            (*num_students)++;
        }
    }

    fclose(file);
}

void delete_course(Student *students, int *num_students) {
    char course[MAX_COURSE_NAME_LENGTH];
    printf("Enter the course name to delete: ");
    scanf("%s", course);

    int deleted = 0;
    for (int i = 0; i < *num_students; i++) {
        if (strcmp(students[i].course_name, course) == 0) {
            // Shift remaining elements to fill the gap
            for (int j = i; j < (*num_students - 1); j++) {
                strcpy(students[j].student_id, students[j+1].student_id);
                strcpy(students[j].course_name, students[j+1].course_name);
                students[j].grade = students[j+1].grade;
            }
            (*num_students)--;
            deleted = 1;
        }
    }

    if (!deleted) {
        printf("Warning: Course does not exist.\n");
    }
}

void calculate_gpa(Student *students, int num_students) {
    for (int i = 0; i < num_students; i++) {
        printf("Student ID: %s\n", students[i].student_id);
        printf("Course Name: %s\n", students[i].course_name);
        printf("Grade: %.2f\n", students[i].grade);
      
        // Calculate GPA
        float gpa = students[i].grade / 20.0;  // Assuming grade is out of 100
        printf("GPA: %.2f\n", gpa);
      
        // Update GPA in the structure
        students[i].grade = gpa;
    }
}

void export_file(Student *students, int num_students) {
    int sub_choice;
    do {
        printf("\n=== Export Menu ===\n");
        printf("1. Sorted in ID (ascending)\n");
        printf("2. Sorted in GPA (descending)\n");
        printf("3. Back to main menu\n");
        printf("Enter your choice: ");
        scanf("%d", &sub_choice);

        switch (sub_choice) {
            case 1:
                sort_by_id(students, num_students);
                break;
            case 2:
                sort_by_gpa(students, num_students);
                break;
            case 3:
                printf("Returning to main menu...\n");
                break;
            default:
                printf("Invalid choice! Please try again.\n");
        }
    } while (sub_choice != 3);
}

void sort_by_id(Student *students, int num_students) {
    // Use bubble sort algorithm to sort by student ID in ascending order
    for (int i = 0; i < num_students - 1; i++) {
        for (int j = 0; j < num_students - i - 1; j++) {
            if (strcmp(students[j].student_id, students[j+1].student_id) > 0) {
                // Swap students
                Student temp = students[j];
                students[j] = students[j+1];
                students[j+1] = temp;
            }
        }
    }

    char file_name[100];
    printf("Enter the file name to export: ");
    scanf("%s", file_name);

    FILE *file = fopen(file_name, "w");
    if (file == NULL) {
        printf("Error opening file.\n");
        return;
    }

    for (int i = 0; i < num_students; i++) {
        fprintf(file, "%s %s %.2f\n", students[i].student_id, students[i].course_name, students[i].grade);
    }

    fclose(file);

    printf("Export successful.\n");
}

void sort_by_gpa(Student *students, int num_students) {
    // Use bubble sort algorithm to sort by GPA in descending order
    for (int i = 0; i < num_students - 1; i++) {
        for (int j = 0; j < num_students - i - 1; j++) {
            if (students[j].grade < students[j+1].grade) {
                // Swap students
                Student temp = students[j];
                students[j] = students[j+1];
                students[j+1] = temp;
            }
        }
    }

    char file_name[100];
    printf("Enter the file name to export: ");
    scanf("%s", file_name);

    FILE *file = fopen(file_name, "w");
    if (file == NULL) {
        printf("Error opening file.\n");
        return;
    }

    for (int i = 0; i < num_students; i++) {
        fprintf(file, "%s %s %.2f\n", students[i].student_id, students[i].course_name, students[i].grade);
    }

    fclose(file);

    printf("Export successful.\n");
}

这是一个简单的示例，实现了您所描述的系统要求。您可以根据需要进行修改和扩展。请注意，此代码仅满足基本功能，可能需要根据实际需求进行进一步的错误处理和输入验证。

cx_Oracle.DatabaseError: DPI-1044: value cannot be represented as an Oracle number

这个错误通常是由于 Python 中的浮点数精度问题导致的。在将 Python 中的浮点数传递给 Oracle 数据库时，可能会出现精度损失，从而导致此错误。解决方法是将浮点数转换为 Decimal 类型，然后再传递给 Oracle 数据库。

以下是一个示例代码：

from decimal import Decimal
import cx_Oracle

# 将浮点数转换为 Decimal 类型
value = Decimal('123.456')

# 连接 Oracle 数据库
connection = cx_Oracle.connect('username/password@host:port/service_name')

# 执行 SQL 语句
cursor = connection.cursor()
cursor.execute('INSERT INTO table_name (column_name) VALUES (:1)', [value])
connection.commit()

# 关闭连接
cursor.close()
connection.close()