带开关盒的 C 结构，输入跳行

Question

所以我决定使用我在过去的程序中使用过的开关盒。它按预期工作，除了每种情况的第一行，输入帐户名称跳过它的输入行。我相信这很简单，而且我已经做了一段时间了。下面是代码，只是试图让该行允许输入，而不是保存到文件中，并在提示继续处理我的案例时继续保存输入。

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


struct account 
{
char company_name[256];
int invoice_number;
int invoice_date;
float invoice_amount;

};


int main() 
{
char *end;
char buf[256];
char y;
char n;
char a;
FILE *newacct;
struct account ledger;
newacct = fopen("robco.txt", "a");



printf("Enter Account Name:");
fgets(ledger.company_name, sizeof(ledger.company_name), stdin);
ledger.company_name[strlen(ledger.company_name)-1] = '\0';
printf("Enter Incoive Number:");
fgets(buf, sizeof(buf), stdin);
ledger.invoice_number = strtol(buf, &end, 10);
printf("Enter Invoice Date:");
fgets(buf, sizeof(buf), stdin);
ledger.invoice_date = strtol(buf, &end, 10);
printf("Enter Invoice Amount:");
fgets(buf, sizeof(buf), stdin);
ledger.invoice_amount = strtol(buf, &end, 10);
fprintf(newacct,"%s %d %d %f\n", ledger.company_name, ledger.invoice_number, 
ledger.invoice_date, ledger.invoice_amount);
fclose(newacct);



printf("Would you like to enter more data?:");
scanf("%s", &a);


switch (a){

case'n':

printf("Thanks for your entry!"); //should terminate
fprintf(newacct,"\n%s %d %d %f", ledger.company_name, ledger.invoice_number, 
ledger.invoice_date, ledger.invoice_amount);
fclose(newacct);

return 0;

case'y':    
FILE *newacct;
struct account ledger;
newacct = fopen("robco.txt", "a");

printf("Enter Account Name:"); //the line that keeps skipping in every switch 
case.
fgets(ledger.company_name, sizeof(ledger.company_name), stdin); //it prints 
however it skips this input line.
ledger.company_name[strlen(ledger.company_name)-1] = '\0';
printf("\nEnter Incoive Number:");
fgets(buf, sizeof(buf), stdin);
ledger.invoice_number = strtol(buf, &end, 10);
printf("Enter Invoice Date:");
fgets(buf, sizeof(buf), stdin);
ledger.invoice_date = strtol(buf, &end, 10);
printf("Enter Invoice Amount:");
fgets(buf, sizeof(buf), stdin);
ledger.invoice_amount = strtol(buf, &end, 10);
fprintf(newacct,"%s %d %d %f\n", ledger.company_name, ledger.invoice_number, 
ledger.invoice_date, ledger.invoice_amount);
fclose(newacct);

break;
}
printf("Would you like to enter more data?:");
scanf("%s", &a);


switch (a){

case'n':

printf("Thanks for your entry!"); //should terminate
fprintf(newacct,"\n%s %d %d %f", ledger.company_name, ledger.invoice_number, 
ledger.invoice_date, ledger.invoice_amount);
fclose(newacct);

return 0;

case'y':
FILE *newacct;
struct account ledger;
newacct = fopen("robco.txt", "a");

printf("Enter Account Name:");
fgets(ledger.company_name, sizeof(&ledger.company_name), stdin);
ledger.company_name[strlen(ledger.company_name)-1] = '\0';
printf("Enter Incoive Number:");
fgets(buf, sizeof(buf), stdin);
ledger.invoice_number = strtol(buf, &end, 10);
printf("Enter Invoice Date:");
fgets(buf, sizeof(buf), stdin);
ledger.invoice_date = strtol(buf, &end, 10);
printf("Enter Invoice Amount:");
fgets(buf, sizeof(buf), stdin);
ledger.invoice_amount = strtol(buf, &end, 10);
fprintf(newacct,"%s %d %d %f\n", ledger.company_name, ledger.invoice_number, 
ledger.invoice_date, ledger.invoice_amount);
fclose(newacct);

break;
}
}

Answer 1

这里有一些代码可以帮助您。注意我avoided usingscanf:

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

struct account {
    int account_number;
    char last_name[32];
};

int main(void) {
    char buf[256];
    char *end;
    FILE *newacct;
    struct account ledger;
    newacct = fopen("robco.txt", "a");

    // collect last name from stdin
    printf("Enter last name: ");
    fgets(ledger.last_name, sizeof(ledger.last_name), stdin);
    ledger.last_name[strlen(ledger.last_name)-1] = '\0';

    // collect account number from stdin
    printf("Enter account number: ");
    fgets(buf, sizeof(buf), stdin);
    ledger.account_number = strtol(buf, &end, 10);

    // write to file
    fprintf(newacct, "%s %d\n", ledger.last_name, ledger.account_number);
    fclose(newacct);

    // read and print contents of file
    newacct = fopen("robco.txt", "r");

    while (fscanf(newacct, "%s %d", ledger.last_name, &ledger.account_number) != EOF) {
        printf("%s %d\n", ledger.last_name, ledger.account_number);
    }

    fclose(newacct);
    return 0;
}

关于您的代码的一些简短说明：

• fscanf 和 feof 应该将文件指针作为第一个参数。
• 将对整数的引用传递给fscanf，而不是整数本身。
• 您的结构有一个指向 char 的指针，但在任何时候都没有确定大小和分配内存 - 您可以在运行时动态地 malloc 或在编译时如上所述预先分配它。李>