我在理解何时应该传递指针以及何时指向它的东西时遇到问题。在我的代码:C - 打开文件并通过传递文件指针作为参数读取char字符
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;
}
我得到重大失误编译此,错误是:
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(文件FP)
我知道有几个问题群在这里,但我不知道什么是正确的: 1.我打开正确的论点?两者的argv [0]和argv [1]似乎是我所指定的文件路径..添加此作为打印出我用于获取的argv信息制成: 试验:
printf("There are %d args, %s, %s\n", argc,argv[0],argv[1]);
结果:
There are 2 args, C:\Users\Dell\.CLion2016.2\system\cmake\generated\CheckParenthesis- 5dc89373\5dc89373\Release\CheckPare
nthesis.exe, C:\testing\brackets.txt
- 我在做正确的指针用法吗?
当你作为参数传递时,你不需要解引用文件指针 – dvhh
而参数应该作为'FILE *'而不是'FILE'传递。从'main'调用的是propert,但函数decl不是。它应该是'int checkFile(FILE * fp)' – WhozCraig
和'char fileName = argv [1];'是错误的,它应该是'char * fileName = argv [1];' – dvhh