#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define   MAX_COLS 20
#define   MAX_INPUT 1000
 
int  read_column_numbers( int columns[], int max);

     
int main(void)
{
    int n_columns;
    int columns[MAX_COLS];
    char input[MAX_INPUT];
    char output[MAX_INPUT];
    n_columns=read_column_numbers(columns,MAX_COLS);
    while (gets(input)!=NULL)
    {
        printf("Original input:%s\n",input);
        
        printf("Rearranged line:%s\n",output);
    }
    return EXIT_SUCCESS;
}
int read_column_numbers(int  columns[], int max)
{  
    int num =0;
    int ch;
    while ( num<max && scanf ("%d",&columns[num] )==1
        && columns[num] >=0)
        num+=1;
    if (num %2 != 0){
        puts ("Last column number is not pairded.");
        exit ( EXIT_FAILURE);
    }
     while( (ch=getchar())!='EOF' && ch!='\n')
         ;
     return num;
}
 void rearrange( char *output, char const * input,
     int n_columns, int const columns [])
 {
     int col;
     int output_col;
     int let;

     let = strlen(input);
     output_col = 0;
     for( col =0; col< n_columns; col +=2)(
         
     if (col =0 ;col=n_columns;col +=2){
         int nchars = columns[col + 1]-columns[col]+1;
         if (columns [col]>=len ||
             output_col ==MAX_INPUT -1)
             break;
         if (output_col + nchars > MAX_INPUT -1)
             nchars = MAX_INPUT -output_col -1;
         strncpy( output +output_col,input+columns[col],
             nchars);
         output_col +=nchars;
     } output['output_col'] ='\0';
 }
--------------------Configuration: 1 - Win32 Debug--------------------
Compiling...
1.c
C:\Users\Administrator\Desktop\1.c(51) : error C2059: syntax error : 'if'
C:\Users\Administrator\Desktop\1.c(51) : error C2143: syntax error : missing ';' before ')'
C:\Users\Administrator\Desktop\1.c(53) : error C2065: 'len' : undeclared identifier
C:\Users\Administrator\Desktop\1.c(55) : error C2043: illegal break
C:\Users\Administrator\Desktop\1.c(56) : error C2065: 'nchars' : undeclared identifier
C:\Users\Administrator\Desktop\1.c(61) : error C2015: too many characters in constant
C:\Users\Administrator\Desktop\1.c(61) : error C2466: cannot allocate an array of constant size 0
C:\Users\Administrator\Desktop\1.c(61) : error C2075: 'output' : array initialization needs curly braces
C:\Users\Administrator\Desktop\1.c(62) : error C2059: syntax error : '}'
执行 cl.exe 时出错.

1.obj - 1 error(s), 0 warning(s)

C舊語法。抄代碼的時候，問作者或看清楚是在什麽編譯器下編譯的。

  我自己不知道 所以用了VC6 貌似书中是用ANSI C 两者是不是有区别？

大概是抄代码抄错了，我只是针对错误大致根据前后文修改了下，确保编译通过，不验证代码运行的正确性：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define   MAX_COLS 20
#define   MAX_INPUT 1000

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


int main(void)
{
    int n_columns;
    int columns[MAX_COLS];
    char input[MAX_INPUT];
    char output[MAX_INPUT];
    n_columns=read_column_numbers(columns,MAX_COLS);
    while (gets(input)!=NULL)
    {
        printf("Original input:%s\n",input);
       
        printf("Rearranged line:%s\n",output);
    }
    return EXIT_SUCCESS;
}
int read_column_numbers(int  columns[], int max)
{ 
    int num =0;
    int ch;
    while ( num<max && scanf ("%d",&columns[num] )==1
        && columns[num] >=0)
        num+=1;
    if (num %2 != 0){
        puts ("Last column number is not pairded.");
        exit ( EXIT_FAILURE);
    }
    while( (ch=getchar())!='EOF' && ch!='\n')
        ;
    return num;
}
void rearrange( char *output, char const * input,
               int n_columns, int const columns [])
{
    int col;
    int output_col;
    int let;
   
    let = strlen(input);
    output_col = 0;
    for( col =0; col< n_columns; col +=2){
       
        for (col =0 ;col=n_columns;col +=2){   //if的条件表达式不包含分号，估计是for语句，改for
            int nchars = columns[col + 1]-columns[col]+1;
            if (columns [col]>=let ||
                output_col ==MAX_INPUT -1)
                break;
            if (output_col + nchars > MAX_INPUT -1)
                nchars = MAX_INPUT -output_col -1;
            strncpy( output +output_col,input+columns[col],
                nchars);
            output_col +=nchars;
        } output;   //output['output_col'] ='\0'原语句这样没见过，看你前面定义了output_col，估计是两条语句
        output_col ='\0';
    }  //加了个}
}

编译器告诉你第51行有问题,你去看看,哪里有个变量定义,这种语法是C99才支持的,vc作C编译器的时候,不支持C99标准,把那一行调到函数的最开头即可.

vc是C++编译器,你不以.c作文件名时不会有这种编译错误.

就按提示修改