我制作了一个程序，用于存储学生ID，姓名，姓氏和商标。该程序没有错误，但无法找到第一个输入。
即
input file;
23915746455 James Doe 1
23915741327 John Doe 2
23915741842 Henny Fluffy 3
我的代码会在身份证和姓名搜索中找到约翰和亨尼，但却找不到詹姆斯。我的代码出了什么问题？第一个输入不会被搜索。
我的完整代码在这里;
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
struct Student
{
long long int id;
char firstname[20];
char lastname[20];
int mark;
} student;
void
storeRecord()
{
FILE *fp;
printf("\nEnter Student Details:\n\nID number: ");
scanf("%lld",&student.id);
printf("\nName:");
scanf("%19s",student.firstname);
printf("\nSurname:");
scanf("%19s",student.lastname);
printf("\nMark(0 - 100 integer) : ");
scanf("%d",&student.mark);
fp = fopen("studentfile.txt","a+"); /* check if the file was opened */
if (fp == NULL)
return;
fprintf(fp, "\n%lld\t%s\t%s\t%d\t",
student.id,
student.firstname,
student.lastname,
student.mark);
fclose(fp);
printf("A student record has been added successfully...\n");
getchar();
}
int
compareStudentsById(struct Student lhs, struct Student rhs)
{
return (lhs.id == rhs.id);
}
int
compareStudentsByName(struct Student lhs, struct Student rhs)
{
return (strcmp(lhs.firstname, rhs.firstname) == 0);
}
void
printStudent()
{
printf("\nThe record is found.\n");
printf("\nID: %lld\nName: %s\nSurname: %s\nMark: %d \n",
student.id,
student.firstname,
student.lastname,
student.mark
);
}
void
searchStudent(int(*compare)(struct Student,struct Student), const char *const name, long long int id)
{
FILE *fp;
int found;
int matches;
if (name != NULL)
printf("Searching record with Name = %s.\n", name);
if (id != -1)
printf("Searching record with ID = %lld.\n", id);
found = 0;
fp = fopen("studentfile.txt", "r");
if (fp == NULL)
{
printf("IO error\n");
return;
}
matches = fscanf(fp,"\n%lld\t%s\t%s\t%d\t",
&student.id,
student.firstname,
student.lastname,
&student.mark);
do
{
struct Student other;
if (name != NULL)
strcpy(other.firstname, name);
other.id = id;
matches = fscanf(fp,"\n%lld\t%s\t%s\t%d\t",
&student.id,
student.firstname,
student.lastname,
&student.mark);
if (matches == 4)
found = (compare(student, other) != 0);
} while ((matches == 4) && (found == 0));
if (found != 0)
printStudent();
else
printf("Not found...\n");
getchar();
}
void
searchStudentByName()
{
char studentname[20];
printf("\nEnter student first name: ");
scanf("%19s", studentname);
searchStudent(compareStudentsByName, studentname, -1);
}
void
searchStudentById()
{
long long int id;
printf("\nEnter ID: ");
scanf("%lld", &id);
searchStudent(compareStudentsById, NULL, id);
}
int main()
{
int choice;
choice = 0;
while (choice != 4)
{
printf("\n\tC PROGRAM OF STUDENT DATABASE SYSTEM");
printf("\n1 -> Store a new record in database\n");
printf("2 -> Search a student record by Student First Name\n");
printf("3 -> Search a student record by ID\n");
printf("4 -> Quit Student Database");
printf("\n\n");
printf("Enter your choice : ");
scanf("%d",&choice);
switch(choice)
{
case 1:
storeRecord();
break;
case 2:
searchStudentByName();
break;
case 3:
searchStudentById();
break;
}
}
return 0;
}
答案 0 :(得分：0)
只需移除fscanf循环外的第一个while，即扫描文件的第一行。
您的代码副本已修复
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
struct Student
{
long long int id;
char firstname[20];
char lastname[20];
int mark;
} student;
void
storeRecord()
{
FILE *fp;
printf("\nEnter Student Details:\n\nID number: ");
scanf("%lld",&student.id);
printf("\nName:");
scanf("%19s",student.firstname);
printf("\nSurname:");
scanf("%19s",student.lastname);
printf("\nMark(0 - 100 integer) : ");
scanf("%d",&student.mark);
fp = fopen("studentfile.txt","a+"); /* check if the file was opened */
if (fp == NULL)
return;
fprintf(fp, "\n%lld\t%s\t%s\t%d\t",
student.id,
student.firstname,
student.lastname,
student.mark);
fclose(fp);
printf("A student record has been added successfully...\n");
getchar();
}
int
compareStudentsById(struct Student lhs, struct Student rhs)
{
return (lhs.id == rhs.id);
}
int
compareStudentsByName(struct Student lhs, struct Student rhs)
{
return (strcmp(lhs.firstname, rhs.firstname) == 0);
}
void
printStudent()
{
printf("\nThe record is found.\n");
printf("\nID: %lld\nName: %s\nSurname: %s\nMark: %d \n",
student.id,
student.firstname,
student.lastname,
student.mark
);
}
void
searchStudent(int(*compare)(struct Student,struct Student), const char *const name, int id)
{
FILE *fp;
int found;
int matches;
if (name != NULL)
printf("Searching record with Name = %s.\n", name);
if (id != -1)
printf("Searching record with ID = %d.\n", id);
found = 0;
fp = fopen("studentfile.txt", "r");
if (fp == NULL)
{
printf("IO error\n");
return;
}
do
{
struct Student other;
if (name != NULL)
strcpy(other.firstname, name);
other.id = id;
matches = fscanf(fp,"\n%lld\t%s\t%s\t%d\t",
&student.id,
student.firstname,
student.lastname,
&student.mark);
if (matches == 4)
found = (compare(student, other) != 0);
} while ((matches == 4) && (found == 0));
if (found != 0)
printStudent();
else
printf("Not found...\n");
getchar();
}
void
searchStudentByName()
{
char studentname[20];
printf("\nEnter student first name: ");
scanf("%19s", studentname);
searchStudent(compareStudentsByName, studentname, -1);
}
void
searchStudentById()
{
int id;
printf("\nEnter student first name: ");
scanf("%d", &id);
searchStudent(compareStudentsByName, NULL, id);
}
int main()
{
int choice;
choice = 0;
while (choice != 4)
{
printf("\n\tC PROGRAM OF STUDENT DATABASE SYSTEM");
printf("\n1 -> Store a new record in database\n");
printf("2 -> Search a student record by Student First Name\n");
printf("3 -> Search a student record by ID\n");
printf("4 -> Quit Student Database");
printf("\n\n");
printf("Enter your choice : ");
scanf("%d",&choice);
switch(choice)
{
case 1:
storeRecord();
break;
case 2:
searchStudentByName();
break;
case 3:
searchStudentById();
break;
}
}
return 0;
}