[英]Reading a line from a text file into an array of characters in c
我正在嘗試從文本文件填充數組。 該數組位於以下結構中:
struct ISBN
{
long value;
};
struct Author
{
char authorName[60];
};
struct Book
{
char *bookTitle;
struct Author bookAuthor;
struct ISBN bookID;
};
我試圖編寫一個fillin函數,該函數采用Book類型的文件和結構,如下所示:
void fillin (FILE * file, struct Book * bk)
{
bk->bookTitle =(char*) malloc(1000);
size_t n = 0;
int c;
file=fopen("book.txt","r");
while ((c = fgetc(file)) != '\n')
{
bk->bookTitle[n++] = (char) c;
}
bk->bookTitle[n] = '\0';
fscanf(file,"%s", &bk->bookAuthor.authorName);
fscanf(file,"%lld",&bk->bookID.value);
//fscanf(file,"%s", &bk->bookTitle);
}
文件book.txt具有以下數據:
UNIX Network Programming
W. Richard Stevens
0131411551
問題是,它無法掃描數組,我想從文本文件填充bookTitle和autherName數組。
以下行是錯誤的:
fscanf(file,"%s", &bk->bookAuthor.authorName);
當您掃描字符串時,字符數組已經是一個指針,因此您無需獲取其地址(&)。 嘗試:
fscanf(file,"%s", bk->bookAuthor.authorName);
為了安全起見(如果是長字符串),可以使用以下功能:
char * fgets ( char * str, int num, FILE * stream );
因此:
fgets(bk->bookAuthor.authorName, 60, file);
如果該行太長,則該字符串的其余部分將不會被復制。如果執行此操作,則可能必須檢查該字符串是否尚未終止,並丟棄其余字符,直到換行為止。 (例如while ((c = fgetc(file)) != '\\n');
)。 \\ n字符被復制到其中,因此您必須找到並刪除它:
bk->bookAuthor.authorName[59] = 0; // make sure it is null-terminated
int last = strlen(bk->bookAuthor.authorName)-1;
if (bk->bookAuthor.authorName[last] == '\n') {
bk->bookAuthor.authorName[last] = 0; // read whole line
}
else ; // terminated early
您還可以使用fscanf
限制字符,並使用以下命令讀取空格:
char c;
scanf(file, "%60[^\n]%c", bk->bookAuthor.authorName, c);
if (c=='\n') {
// we read the whole line
} else {
// terminated early, c is the next character
//if there are more characters, they are still in the buffer
}
要丟棄該行的其余部分,您可以執行以下操作
while (c != '\n' && c != EOF) c = fgetc(file);
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