我的程序用于删除数据文件中的记录。我会要求用户输入他想要删除的"记录编号"。然而，当我使用strcmp这个函数来比较两个字符串时，它不起作用。
问题：无法使用strcmp删除某些记录并将更新的数据放入新文件
这是我的代码：
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main(){
Del_menu();
return 0;
}
// function1
int Del_menu() {
while (1) {
printf("Please enter a record number you wanted to delete : ");
Del();
printf("nDo u want to delete other record? Enter 'y' for yes and
'n' for no :");
char ans;
scanf(" %c", &ans);
if (ans == 'N' || ans == 'n') {
break;
}
}
}
//function2
int Del(){
FILE *sfr = fopen("stock.txt", "r");
//just for me getting total number,you can igone this
char *str;
int total;
total=0;
while (!feof(sfr)){
str = fgetc(sfr);
if(str == 'n') {
total++;
}
}
total = (total/9);
fclose(sfr);
FILE *fileptr1, *fileptr2;
char filename[40] = "data.txt";
int total = 0;
int total_1 = 0 ,total_2 = 0, i = 0 , temp;
char itemrecord [40][40];
char quantity [40][40];
char weight [40][40];
char itemname [40][40];
char catagory [40][40];
char recipient [40][40];
char final_destination [40][40];
char status [40][40];
fseek(stdin, 0, SEEK_END);
fflush(stdin);
i++;
total--;
}
FILE *fileptr1, *fileptr2;
char filename[40]="stock.txt";
fileptr1 = fopen(filename, "r");
char buffer [50];
while(total_1!=0){
fgets(recordnum[i],50,fileptr1);
fgets(itemname[i],50,fileptr1);
fgets(itemrecord[i],50,fileptr1);
fgets(catagory[i],50,fileptr1);
fgets(quantity[i],50,fileptr1);
fgets(weight[i],50,fileptr1);
fgets(recipient[i],50,fileptr1);
fgets(final_destination[i],50,fileptr1);
fgets(status[i],50,fileptr1);
fgets(buffer, 50,fileptr1);
fclose(fileptr1);
fclose(fileptr2);
i++;
total_1--;
}
char del_data[41]; //get user input
fgets(del_data,50,stdin);
del_data[strlen(del_data) - 1] = ' ';
printf("nyou have entered :%sn", del_data);
printf("nRecord in file before delete:n");
printf("Total record: %dn",total);
i=0;
while(total_2!=0){
printf("%s%s%s%s%s%s%s%s%sn",recordnum[i],itemrecord[i],quantity[i],
weight[i],itemname[i], catagory[i],recipient[i],
final_destination[i],status[i]);
i++;
total_2--;
}
rewind(fileptr1);
fseek(stdin, 0, SEEK_END);
fileptr2 = fopen("copy.c", "w"); //stored the data after deleted
total_3=total_3 -1;
i=0;
while(total!=0){
if ( strcmp(recordnum[i],del_data) != 0){
printf("%s",recordnum[i]); //for me checking is it successful
fprintf(fileptr2,"%s%s%s%s%s%s%s%s%sn",recordnum[i],itemrecord[i],
quantity[i],weight[i],itemname[i], catagory[i],recipient[i],
final_destination[i],status[i]);
i++; total--;}
}
remove(filename);
// rename the file copy.c to original name
rename("copy.c", filename);
} // end of function 2
结果：
Please enter a record runber you want to delete: 1001
You enterd: 1001
Record in file before deleted:
Total:3
1001
Orange Laptop Computer DX5
235524
Electronics
1
1.8 kg
Chan
Mong Kok
Delivery
1002
Japanese Garden Pear Gift Box
300522
Food
2
4.2 kg
Cheung
Yuen Long
Arrival
1003
Koppo Badminton Racket GPX-15
77524
Fashion
3
0.6 kg
Lee Siu Yu
Fortress Hill
Warehouse
1001 // not exist after i finish this code
1002 // just for I debugging now
1003 // here is my problem* mean that cannot delete record successful
DO you want to delete other record?Enter'y' for yes, 'n' for no: n
当您读取用户的选择时，您会小心地删除fgets()存储在缓冲区中的尾随换行符，但不会对读取到数组中的数据应用相同的处理方法。文件中的每个字段似乎都在单独的一行上，因此在读取到数组中的数据中确实存在换行符。因此，比较失败，因为字符串确实不同。
最简单的解决方案是停止从用户输入中剥离尾部换行符。这段代码还有很多其他问题，但做出这样的更改至少应该能让它按照您所要求的方式工作。