I'm working on a function that is supposed to read a file and I need the first line of the text file to be converted to an integer. The function takes the file in as a parameter, char *filename.
However, I'm getting an error when opening the file.
The error is the following: "passing argument of 2 of 'fopen' makes pointer from integer without a cast [-Wint-conversion] gcc"
FILE *fp = fopen(filename, 'r'); //Line with error
char str[6]; //since the first line is a 5 digit number
fgets(str, 6, fp);
sscanf(str, "%d", *number); //number is the pointer I'm supposed to save this value to, it is also a parameter for the function
I'm very new to C. So, I would appreciate any help. Thanks
If you will look through the description of the function fopen you will see that it is declared like
FILE *fopen(const char * restrict filename, const char * restrict mode);
That is the both parameters have the pointer type const char *.
So instead of the integer character constant 'r' as the second argument you need to use string literal "r"
FILE *fp = fopen(filename, "r");
Also you have to write
sscanf(str, "%d", &number);
instead of
sscanf(str, "%d", *number);
if number has the type int. Or if it has the type int * then you need to write
sscanf(str, "%d", number);
And it is desirable to declare the character array as having at least 7 characters to allow to read also the new line character '\n' of the record
char str[7]; //since the first line is a 5 digit number
fgets(str, sizeof( str ), fp);
Otherwise a next call of fgets can read an empty string.