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Fgets and non-printable characters

Can fgets read non-printable characters into a given char * (I can't seem to)? And if not, what alternative would allow the maximum number of input characters from the stream to char *?

EDIT (for my specific case)

I have an encoder that prints "Le \ D7" to stdout, which is passed to the decoder, which fetches it from its stdin using:

if( fgets( inputChars, MAX_BYTES_IN, stdin ) == NULL )
{
    fprintf( stderr, "Trouble getting input\n" );
    return 0;
}

while( inputChars[crntChar] != '\0' && inputChars[crntChar] != '\n' )
{
    printf( "Value %d: %d\n", crntChar, inputChars[crntChar]);
    crntChar++;
}

This leads to:

Value 0: 76
Value 1: 101
Value 2: -41

Using fgetc has the same result

+3


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3 answers


You get a weird value because of the unsigned integer conversion.

char x = 198;

printf("x = %d\n", x);
printf("(unsigned) x = %u\n", (unsigned) x);
printf("(unsigned char) x = %d\n", (unsigned char) x);

Output:

x = -58
(unsigned) x = 4294967238
(unsigned char) x = 198


Listing (unsigned char)

is what you want.

Please ignore the signed overflow in my code. Note that if you compile GCC and the flag -funsigned-char

, the output will be as follows:

x = 198
(unsigned) x = 198
(unsigned char) x = 198
+1


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The easiest way is to use fgetc()

. fgets()

relies on fgetc()

.

But there are many alternatives, fread()

is one of them. fscanf()

...

fgetc()

while others read both printable and non-printable characters into an array char

. A char

is just 1 byte number encoded in ASCII (or 2 bytes in the case wchar_t

). In C.



no concept of symbols printable

andnon printable

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fgets()

will read one line of a line, in this case read to a new line \n

/ 0x0A

or NULL

/ EOF

.

or perhaps you can use unsigned char * for non-printable ASCII.

in my opinion, yes fgets()

can read non-printable ASCII

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