A mysterious error reported by gcc

mcmay 2014-11-18 07:23:05

各位达人，我用gcc的编译器编译以下程序，但老是在宏定义那里报错，但在VC6上却毫无问题。麻烦各位看看，谢谢！

/*

** This program reads input lines from standard input and prints

** each input line, followed by just some portions of the line, to

** the standard output.

**

** The first input is a lint of column numbers, which ends with a

** negative number. The column numbers are paired and specify

** ranges of columns from the input line that are to be printed.

** For example, 0 3 10 12 -1 indicates that only columns 0 through 3

** and columns 10 through 12 will be printed.

**/



#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#define MAX_COLS	20		/* max # of columns to process */

#define MAX_INPUT   1000	/* max len of input & output lines */

/× 上面的这个宏定义被报错：expected identifier before numeric constant */

int read_column_numbers(int columns[], int max);

void rearrange(char * output, char const * input, int n_columns, int const columns[]);



int main(void)

{

	int n_columns;			/* # of columns to process */

	int columns[MAX_COLS];	/* the columns to process */

	char input[MAX_INPUT];	/* array for input line */

	char output[MAX_INPUT]; /* array for output line */



	/*

	** Read the list of columns numbers

	*/

	n_columns = read_column_numbers(columns, MAX_COLS);



	/*

	 ** Read, process and print the remaining lines of input

	 */

	puts("Input lines (empty line to quit):");

	while(gets(input) != NULL){

		printf("Original input: %s\n", input);

		rearrange(output, input, n_columns, columns);

		printf("Rearranged line: %s\n", output);

		puts("Input lines (empty line to quit):");

	}

	return EXIT_SUCCESS;

}



/*

 ** Read the list of columns numbers, ignoring any beyond the specified maxim.

 */



int read_column_numbers(int columns[], int max)

{

	int num = 0;

	int ch;



	/*

	** Get the numbers, stopping at eof or when a number is < 0.

	*/

	puts("Input the column numbers:");

	while (num < max && scanf("%d", &columns[num]) == 1 && columns[num] >= 0)

			num += 1;



	/*

	 ** Make sure we have an even number of inputs, as they are supposed to be paired.

	 */

	if(num % 2 != 0){

		puts("Last column number is not paired.");

		exit(EXIT_FAILURE);

	}

	/*

	 ** Discard the rest of the line that contained the final number.

	 */

	while ((ch = getchar()) != EOF && ch != '\n')

			;

	return num;

}



/*

** Process as line of input by concatenating the characters from the indicated columns.

** The output line is the NUL terminated.

*/



void rearrange(char * output, char const * input, int n_columns, int const columns[])

{

	int col;			/* subscript for columns array */

	int output_col;		/* output column counter */

	int len;			/* length of input line */



	len = strlen(input);

	output_col = 0;



	/*

	** Process each pair of column numbers.

	*/

	for(col = 0; col < n_columns; col += 2){

		int nchars = columns[col+1] - columns[col] + 1;



		/*

		**	If the input line isn't this long or the output array is full, we're done.

	    */

		if(columns[col] >= len || output_col == MAX_INPUT - 1)

			break;



		/*

		** If there isn't room in the output array, only copy what will fit.

		*/

		if(output_col + nchars > MAX_INPUT - 1)

			nchars = MAX_INPUT - output_col - 1;

		/*

		** Copy the relevant data.

		*/

		strncpy(output + output_col, input + columns[col], nchars);

		output_col += nchars;

	}

	output[output_col] = '\0';

}