[英]I keep getting a segmentation fault and I don't know why
我正在用C编写一个链表程序,我试图将链表写入文件。 在程序询问用户他们想要保存文件的名称之后,我输入名称并按Enter键然后我得到分段错误并退出程序。 我迷失了,试图找出原因。 我唯一能想到的是do..while
循环,但我在我的程序中使用其他代码,它工作正常。 提前致谢!
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct Inventory {
int partID;
int quantity;
float price;
struct Inventory *next;
};
void saveFile(struct Inventory**);
int main()
{
struct Inventory *first = address location of first structure in list;
saveFile(&first);
return 0;
}
void saveFile (struct Inventory **firstPtr)
{
struct Inventory *prev = NULL;
char ext[5] = ".csv";
char fileName[15];
char c;
FILE *fp;
printf(" What would you like to save your linked list as, up to 14 characters: ");
scanf("%s", fileName);
strcat(fileName, ext);
if((fp = fopen(fileName, "r")) != NULL) {
printf(" File already exists. Would you like to overwrite? [Y/N] ");
scanf("\n%c", &c);
if(c == 'Y' || c == 'y') {
fclose(fp);
fp = fopen(fileName, "w+");
} else {
printf(" Would you like to add to the list? [Y/N] ");
if(c == 'y' || c == 'Y') {
fclose(fp);
fp = fopen(fileName, "a");
} else {
fclose(fp);
return;
}
}
} else {
fclose(fp);
fp = fopen(fileName, "w+");
}
do {
prev = *firstPtr;
fprintf(fp, "%d,%d,%f\n", prev->partID, prev->quantity, prev->price);
prev = prev->next;
} while (prev->next != NULL);
fclose(fp);
}
您的循环不会防止第一个条目可能为NULL
,请尝试使用以下循环链接列表:
while (prev) {
fprintf(fp, "%d,%d,%f\n", prev->partID, prev->quantity, prev->price);
prev = prev->next;
}
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