I've a text file with following contents:
"abc","def","ghi"
The following works to read the file contents properly:
int main()
{
char name[1024] = {0};
FILE *file = fopen("file.txt", "r");
while(1)
{
if (fscanf(file, " %[\",]s ", name) == EOF)
break;
if (fscanf(file, " %[a-zA-Z]s ", name) == EOF)
break;
printf("%s\n", name);
}
return 0;
}
However, the following fails:
int main()
{
char name[1024] = {0}, garbage[5];
FILE *file = fopen("file.txt", "r");
while(1)
{
if (fscanf(file, " %[\",]s%[a-zA-Z]s ", garbage, name) == EOF)
break;
printf("%s\n", name);
}
return 0;
}
I'm using MSVC++ 08. What am I missing? I'm looking for a solution with single fscanf()
in the while
loop.
It works??? Pure bad luck :-)
Your conversion specifications mean
" %[\",]s "
^= optionally skip whitespace
^== read a literal 's'
^^^^^^=== read an unlimited string of quotes and commas
^========= optionally skip whitespace
and
" %[a-zA-Z]s "
^= optionally skip whitespace
^== read a literal 's'
^^^^^^^^^=== read an unlimited string of letters
^============ optionally skip whitespace
and
" %[\",]s%[a-zA-Z]s "
^= optionally skip whitespace
^== read a literal 's'
^^^^^^^^^=== read an unlimited string of letters
^============ read a literal 's'
^^^^^^============= read an unlimited string of quotes and commas
^=================== optionally skip whitespace
I think you want
" %4[\",]%1023[a-zA-Z] "
^= optionally skip whitespace
^^^^^^^^^^^^^== read a string of at most 1023 letters
^^^^^^^=============== read a string of at most 4 quotes and commas
^====================== optionally skip whitespace
Other than that, scanf
returns the number of successful conversions or EOF on error. You're comparing the result value with EOF when you should be comparing to 1 (or 2, or whatever): compare to the number of conversions you expect.
if (scanf() == 3) /* expected 3 conversions */
{ /* ok */ }
else { /* oops, something went wrong */ }
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