我正在尝试创建具有五种功能的电话簿。我已经形成了第一个功能，它记录了人们的知识。但是，我无法成功从文件中搜索一个人（不是所有人）知识的第二个功能。
要运行此功能（“”display（）function“”）我想要用户名来搜索并在屏幕上显示该名称的知识。我写了一些东西，但它没有用。问题是display（）函数。如何只阅读一行并将其打印在屏幕上？提前谢谢。
#include <stdio.h>
#include <stdlib.h> // "stdlib" library contains of exit() and malloc function
#include <Windows.h> // "Windows" library contains of Sleep() function
#include <string.h> // "string" library contains of strcmp() function
struct personKnowledge
{
char number[16];
char name[16];
char surname[16];
};
void newRecord();
void display();
void deletE();
void add();
void update();
FILE *ptrFILE;
int main()
{
int choice;
printf("\n\t\t *-* Phone Book Program *-*");
do
{
printf("\n\n\t\t 1) New record"); // The options are being presented to user
printf("\n\n\t\t 2) Display person knowledge");
printf("\n\n\t\t 3) Delete someone");
printf("\n\n\t\t 4) Add new person");
printf("\n\n\t\t 5) Update person knowledge");
printf("\n\n\t\t 6) Exit");
printf("\n\n\nEnter your choice: ");
scanf("%d", &choice);
switch (choice)
{
case 1:
{
newRecord();
break;
}
case 2:
{
display();
break;
}
case 3:
{
break;
}
case 4:
{
break;
}
case 5:
{
break;
}
case 6:
{
printf("\nWorking has been completed.\n");
exit(0);
break;
}
default:
{
printf("\nWrong entry! The program has been terminated.\n");
}
}
} while (choice >=1 && choice <=6 );
return 0;
}
void newRecord()
{
system("cls"); // Screen is being cleaned
if ((ptrFILE = fopen("Phone Book.txt", "w")) == NULL)
{
printf("The file couldn't open\n");
}
else
{
struct personKnowledge *p; // p means person
p = (struct personKnowledge *)malloc(sizeof(struct personKnowledge)); // Memory is being allocated
fflush(stdin);
printf("\n\nDetermine person name: "); // User is entering the person's knowledge and they are being saved in file
gets(p->name);
printf("Determine %s's surname: ", p->name);
gets(p->surname);
printf("Determine %s's number: ", p->name);
gets(p->number);
fprintf(ptrFILE, "Name\t\t\t\tSurname\t\t\t\t\tNumber\n");
fprintf(ptrFILE, "--------\t\t ----------------\t\t\t---------------------\n");
fprintf(ptrFILE, "\n%s%33s%38s\n", p->name, p->surname, p->number);
fclose(ptrFILE);
free(p);
printf("Please wait, information is saving to file..\n");
Sleep(1000);
printf("*-* Saving operation has been completed. *-*");
}
fclose(ptrFILE);
}
void display()
{
struct personKnowledge *s; // s means searching
char name[16];
if ((ptrFILE = fopen("Phone Book.txt", "r")) == NULL)
{
printf("The file couldn't open\n");
}
else
{
fseek(ptrFILE, 0L, SEEK_SET);
printf("Express name which you search: ");
gets(s->name);
while (!feof == NULL)
{
fscanf(ptrFILE,"%s", &name);
if (strcmp(s->name, name) == 0)
{
printf("qawsdsdf");
}
}
}
fclose(ptrFILE);
}
答案 0 :(得分：2)
在回答您的一个问题时，我建议您在display()
while (!feof == NULL) // wrong way to use feof
{
fscanf(ptrFILE,"%s", &name); // might overflow the string space
if (s->name == name) // wrong way to compare strings
{
printf("qawsdsdf"); // missing newline?
}
}
用这个
while (fgets(name, sizeof(name), ptrFILE) != NULL) // safer way to read to a small buffer
{
name [ strcspn(name, "\r\n") ] = 0; // remove trailing newline etc
if (strcmp(s->name, name) == 0) // compare the strings
{
printf("qawsdsdf\n"); // added newline
}
}
编辑在任何情况下，您发布的代码甚至无法正确编译：
while (!feof == NULL)
是垃圾，应该是
while (!feof(ptrFILE))
虽然正如我所说的那样not the way to use feof无论如何。如果您启用并处理了编译器警告，则不会发生这种情况。
答案 1 :(得分：0)
我的解决方案是更改文件的格式化方式
fprintf(ptrFILE, "\n%s%33s%38s", p->name, p->surname, p->number);
因为如果你使用程序来检索信息，那么每次写入时都不需要用一堆垃圾标题来填充它。 然后，我编辑了显示功能，以便能够检索所述信息。
void display()
{
struct personKnowledge s; // s means searching
char name[16];
char sname[16];
char number[16];
char surname[16];
if ((ptrFILE = fopen("Phone Book.txt", "r")) == NULL)
{
printf("The file couldn't open\n");
}
else
{
printf("Express name which you search: ");
scanf("%s", &sname);
do
{
fscanf(ptrFILE,"%s%33s%38s", &name, &surname, &number);
if (strcmp(sname, name) == 0)
{
printf("%s %s %s", name, surname, number);
}
}
while (strcmp(sname, name) != 0);
}
}
P.S。我自己还是新手，我认为我不能给你一个很好的解释，为什么我的代码工作而你的代码不工作。但我可以说，当我对代码进行故障排除时，每次写入文件的那些标题都是问题的主要部分。
答案 2 :(得分：0)
我认为这些微小的变化将解决您的问题
s = (struct personKnowledge *)malloc(sizeof(struct personKnowledge)); fscanf(ptrFILE, "Name\t\t\t\tSurname\t\t\t\t\tNumber\n");
fscanf(ptrFILE, "--------\t\t ----------------\t\t\t---------------------\n");
while (!feof(ptrFILE)) fscanf(ptrFILE, "\n%s%33s%38s\n", s->name, s->surname, s->number) if (strcmp(name,s->name) == 0) 修改后的显示功能
void display(){
struct personKnowledge *s;
s = (struct personKnowledge *)malloc(sizeof(struct personKnowledge)); // Memory is being allocated for s
fflush(stdin);
char name[16];
if ((ptrFILE = fopen("Phone Book.txt", "r")) == NULL)
{
printf("The file couldn't open\n");
}
else
{
fseek(ptrFILE, 0L, SEEK_SET);
printf("Express name which you search: ");
scanf("%s",name); //the name you want to retrieve
fscanf(ptrFILE, "Name\t\t\t\tSurname\t\t\t\t\tNumber\n");
fscanf(ptrFILE, "--------\t\t ----------------\t\t\t---------------------\n"); //when we read the file for first time we need to start from the first location of person data, this is a trick to make ptrFILE reach there
fflush(stdin);
while (!feof(ptrFILE))
{
fscanf(ptrFILE, "\n%s%33s%38s\n", s->name, s->surname, s->number);//same format as fprintf used in newRecord
if (strcmp(name,s->name) == 0) //comparison
{
printf("qawsdsdf");
}
}}fclose(ptrFILE);}