[英]C - Opening a file and reading char by char with passing the file pointer as argument
我在理解何時應該傳遞指針以及指針指向的東西時遇到了麻煩。 在我的代碼中:
int checkFile(FILE fp)
{
int c;
while((c = fgetc(*fp)) != EOF)
{
putchar(c);
}
fclose(*fp);
}
int main(int argc, char *argv[])
{
FILE *fp = fopen(argv[0], "r");
char fileName = argv[1];
if(argc > 2)
{
printf("Please supply a file!\n");
printf("usage: CheckParenthesis <file name>\n");
}
if (fp == NULL)
{
printf("Error! trying to open the file\n");
return 1;
}
else
{
checkFile(fp);
}
return 0;
}
我在編譯此文件時遇到重大錯誤,錯誤是:
C:\Users\Dell\ClionProjects\CheckParenthesis\CheckParenthesis.c: In function 'checkFile':
C:\Users\Dell\ClionProjects\CheckParenthesis\CheckParenthesis.c:17:22: error: invalid type argument of unary '*' (have 'FILE')
while((c = fgetc(*fp)) != EOF)
^
C:\Users\Dell\ClionProjects\CheckParenthesis\CheckParenthesis.c:21:12: error: invalid type argument of unary '*' (have 'FILE')
fclose(*fp);
^
C:\Users\Dell\ClionProjects\CheckParenthesis\CheckParenthesis.c: In function 'main':
C:\Users\Dell\ClionProjects\CheckParenthesis\CheckParenthesis.c:28:21: warning: initialization makes integer from pointer without a cast
char fileName = argv[1];
^
C:\Users\Dell\ClionProjects\CheckParenthesis\CheckParenthesis.c:41:9: error: incompatible type for argument 1 of 'checkFile'
checkFile(fp);
^
C:\Users\Dell\ClionProjects\CheckParenthesis\CheckParenthesis.c:12:5: note: expected 'FILE' but argument is of type 'struct FILE *'
int checkFile(FILE fp)
我知道這里有很多問題,但是我不知道什么是正確的:1.我是否打開正確的論點? argv [0]和argv [1]都似乎是我指定的文件路徑。將其添加為打印出來的打印件是為了獲取argv信息:測試:
printf("There are %d args, %s, %s\n", argc,argv[0],argv[1]);
結果:
There are 2 args, C:\Users\Dell\.CLion2016.2\system\cmake\generated\CheckParenthesis- 5dc89373\5dc89373\Release\CheckPare
nthesis.exe, C:\testing\brackets.txt
唷! 因此, checkfile()
應該使用文件指針而不是文件。 將int checkFile(FILE fp)
更改為int checkFile(FILE* fp)
,然后在稍后查看時,應將任何*fp
更改為fp
您的代碼應如下所示:
int checkFile(FILE* fp) {
int c;
while ((c = fgetc(fp)) != EOF) {
putchar(c);
}
fclose(fp);
}
int main(int argc, char *argv[]) {
FILE *fp = fopen(argv[0], "r");
char* fileName = argv[1]; // thanks to dvhh in the comments
if (argc > 2) {
printf("Please supply a file!\n");
printf("usage: CheckParenthesis <file name>\n");
}
if (fp == NULL) {
printf("Error! trying to open the file\n");
return 1;
} else {
checkFile(fp);
}
return 0;
}
那應該有幫助,也可以查看您的編譯方式嗎(假設您使用的是gcc)
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