c - 使用 fscanf() 从文本文件读取

Question

我无法弄清楚我的代码中出了什么问题。我认为我的 while 循环没有正确读取文件，我试图打印出客户名称，但没有显示任何内容。

例如，我有一个这样的文件。

Smith 3 Sweater $22.50
Reich 3 Umbrella $12.50
Smith 1 Microwave $230.00
Lazlo 1 Mirror $60.00
Flintstone 5 Plate $10.00
Lazlo 1 Fridge $1200.00
Stevenson 2 Chair $350.00
Smith 10 Candle $3.50
Stevenson 1 Table $500.00
Flintstone 5 Bowl $7.00
Stevenson 2 Clock $30.00
Lazlo 3 Vase $40.00
Stevenson 1 Couch $800.00

这是我的代码:

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

struct orders_tag {
    int number_of_orders;
    char item_name[20];
    double price;
};

typedef struct orders_tag order;

struct customer_tag {
    char name[30];
    order total_order[100];
};

typedef struct customer_tag customer;

int main(void) {
    FILE *infile;
    customer cus_array[20];
    customer c;
    int customerCounter = 0;

    setvbuf(stdout, NULL, _IONBF, 0);

    infile = fopen("input.txt", "r");

    if (infile == NULL) {
        printf("Couldn't open the fire.");
        return 1;
    }

    while (fscanf(infile, "%s %d %s %lf", c.name,  c.total_order[customerCounter].number_of_orders
        , c.total_order[customerCounter].item_name,  c.total_order[customerCounter].price) != EOF) {
        cus_array[customerCounter] = c;
        customerCounter++;
    }

    int j;
    for(j = 0; j < customerCounter; j++) {
        printf("%s", cus_array[j].name);
    }
    return 0;
}

Answer 1

您的代码中有很多问题。

第 1 点:您必须向 fscanf() 提供地址 [指针]来存储该值。改变

while (fscanf(infile, "%s %d %s %lf", c.name,  c.total_order[customerCounter].number_of_orders
    , c.total_order[customerCounter].item_name,  c.total_order[customerCounter].price) != EOF) {

至

while (fscanf(infile, "%s %d %s %lf", c.name,  &c.total_order[customerCounter].number_of_orders
    , c.total_order[customerCounter].item_name,  &c.total_order[customerCounter].price) != EOF) {

第2点:在你的输入文件中，每行的输入是

Smith 3 Sweater $22.50

因此，您必须将 fscanf() 格式更改为 "%s %d %s $%lf" 以匹配输入。因此，始终建议检查 fscanf() 及其系列的重新运行值，以确保正确扫描所有值。

第 3 点:customerCounter 变量使用错误。

第 4 点:根据您的输入文件，total_order 不必是数组。

检查下面的代码。它有效。

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

struct orders_tag {
        int number_of_orders;
        char item_name[20];
        double price;
};

typedef struct orders_tag order;

struct customer_tag {
        char name[30];
        order total_order;   //array not required
};

typedef struct customer_tag customer;

int main(void) {
        FILE *infile;
        customer cus_array[20];
        customer c;
        int customerCounter = 0;

        setvbuf(stdout, NULL, _IONBF, 0);

        infile = fopen("input.txt", "r");

        if (infile == NULL) {
                printf("Couldn't open the fire.");
                return 1;
        }

        while (fscanf(infile, "%s %d %s $%lf", c.name,  &c.total_order.number_of_orders
                                , c.total_order.item_name,  &c.total_order.price) != EOF) {//notice the changes here
                cus_array[customerCounter] = c;
                customerCounter++;
                if (customerCounter == 20) break; // memory allocated for only 20 elements
        }

        int j;
        for(j = 0; j < customerCounter ; j++) {
                printf("Customer :%10s, Number of order : %2d, Item : %10s, Price : $%f\n",
                        cus_array[j].name, cus_array[j].total_order.number_of_orders,cus_array[j].total_order.item_name, cus_array[j].total_order.price);
        }
        return 0;
}