NEWLINE.cpp

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// checking for newline (CR or CR-LF)
 
 
#include <stdio.h>
#include <stddef.h>
 
 
int main ()
{
    // determine the byte sequence that corresponds to the '\n'
    // source character, i.e., one of
    //   <CR>     -- Apple II and Mac OS
    //   <LF>     -- UNIX systems
    //   <CR><LF> -- CP/M, DOS, Windows
    //   <LF><CR> -- unknown
 
    char fname [256];
    if (0 == tmpnam (fname))
        return 1;
 
    FILE *fp = fopen (fname, "w");
    if (0 == fp)
        return 2;
 
    fprintf (fp, "%s", "a\nb");
    fclose (fp);
 
    fp = fopen (fname, "rb");
    if (0 == fp)
        return 3;
 
    char buffer [32] = "";
 
    size_t nbytes = fread (buffer, 1, sizeof buffer, fp);
 
    fclose (fp);
    remove (fname);
 
    char *pc;
 
    for (pc = buffer; *pc && *pc != '\n'; ++pc);
 
    if ('\0' == *pc) {
 
        for (pc = buffer; *pc && *pc != '\r'; ++pc);
 
        if ('\0' == *pc) {
 
#if 'A' == '\x41'   // ASCII
 
            // no newline?
            return 4;
            
 
#elif 'A' == '\xc1'   // EBCDIC
 
            
            for (pc = buffer; *pc && *pc != '\x15'; ++pc);
 
            if ('\0' == *pc) {
                // no newline?
                return 4;
            }
 
            printf ("#define _RWSTD_NEWLINE \"\\x15\"\n");
            printf ("#define _RWSTD_NEWLINE_NEL\n");
 
#endif   // ASCII or EBCDIC
 
        }
        else {
 
            printf ("#define _RWSTD_NEWLINE \"\\r\"\n");
            printf ("#define _RWSTD_NEWLINE_CR\n");
        }
    }
    else {
        if ('\r' == pc [1]) {
            printf ("#define _RWSTD_NEWLINE \"\\n\\r\"\n");
            printf ("#define _RWSTD_NEWLINE_LF_CR\n");
        }
        if ('\r' == pc [-1]) {
            printf ("#define _RWSTD_NEWLINE \"\\r\\n\"\n");
            printf ("#define _RWSTD_NEWLINE_CR_LF\n");
        }
        else {
            printf ("#define _RWSTD_NEWLINE \"\\n\"\n");
            printf ("#define _RWSTD_NEWLINE_LF\n");
        }
    }
 
    return 0;
}