c - 如何添加不断询问用户输入并将所有输入保存到文件

Question

我的代码有一个问题:每当我想添加一个新病人时，就会发生一些可疑的事情。如果我一次写一个病人然后退出登记，我输入的病人就会在文件中找到。但是，如果我一次写入多个患者，则只会保存最后一个患者的输入，其余的则不会保存。我相信这与我的阵列有关，但我无法确定。有什么建议吗？

代码如下:

    FILE *patientfile;
    char answer;

    patientfile= fopen("test.txt", "a");
    if (!patientfile)
        {
        printf(" Failed to open file.\n");
        }

    do
    {
        int i=0;

        printf(" Enter details of patient %d\n\n", i+1);
    
        printf(" Patients first name: ");
            scanf("%s",arr_patient[i].fname);
        printf(" Last name: ");
            scanf("%s",arr_patient[i].lname);
        printf(" Personnummer: ");
            scanf("%d", &arr_patient[i].birthdate);
        printf(" Bildref: ");
            scanf("%d", &arr_patient[i].bildref);
        
        printf(" Do you want to add someone else?: (y/n):");
            scanf(" %c",&answer);
    
        i++;
    
    }while(answer != 'n');

    int i = 0;

    fprintf(patientfile," %s\t%s \n ", arr_patient[i].fnamn,arr_patient[i].lnamn);
    fprintf(patientfile," %d \n",arr_patient[i].birthdate);
    fprintf(patientfile," %d \n",arr_patient[i].bildref);



    fclose(patientfile);

    }

编辑:问题已解决!谢谢大家!

Answer 1

这是应该做的(我在代码中嵌入了关于问题的注释)

char answer;
// NOTE: this must be outside the loop
int i=0;
do
{
    printf(" Enter details of patient %d\n\n", i+1);

    printf(" Patients first name: ");
    scanf("%s",arr_patient[i].fname);
    printf(" Last name: ");
    scanf("%s",arr_patient[i].lname);
    printf(" Personnummer: ");
    scanf("%d", &arr_patient[i].birthdate);
    printf(" Bildref: ");
    scanf("%d", &arr_patient[i].bildref);

    printf(" Do you want to add someone else?: (y/n):");
        scanf(" %c",&answer);

    i++;

}while(answer != 'n');

FILE *patientfile = fopen("test.txt", "a");
if (!patientfile) printf(" Failed to open file.\n");

// NOTE: You need to loop over the array and write all the patients to the file
for(int j=0; j<i; j++)
{
    fprintf(patientfile," %s\t%s \n ", arr_patient[j].fnamn,arr_patient[j].lnamn);
    fprintf(patientfile," %d \n",arr_patient[j].birthdate);
    fprintf(patientfile," %d \n",arr_patient[j].bildref);
}
fclose(patientfile);

但实际上您并不需要数组。您可以像这样直接将患者写入文件:

FILE *patientfile = fopen("test.txt", "a");
if (!patientfile) printf(" Failed to open file.\n");
char answer;
int i=0;
do
{
    // change patient_struct to your structure name
    patient_struct patient;
    printf(" Enter details of patient %d\n\n", i+1);

    printf(" Patients first name: ");
    scanf("%s",patient.fname);
    printf(" Last name: ");
    scanf("%s",patient.lname);
    printf(" Personnummer: ");
    scanf("%d", &patient.birthdate);
    printf(" Bildref: ");
    scanf("%d", &patient.bildref);

    fprintf(patientfile," %s\t%s \n ", patient.fnamn, patient.lnamn);
    fprintf(patientfile," %d \n", patient.birthdate);
    fprintf(patientfile," %d \n", patient.bildref);

    printf(" Do you want to add someone else?: (y/n):");
        scanf(" %c",&answer);

    i++;

}while(answer != 'n');
fclose(patientfile);