ex_1-19.c

   1 /*
   2
   3 maxline
   4
   5
   6 function: discard newline
   7         for loop through buffer looking for terminator
   8                 if current postion is newline, set position to terminator
   9
  10
  11 function: reverse
  12         for find end of buffer as integer
  13         move back one space
  14         for loop reverse through string printing out chars one at a time
  15
  16
  17
  18 function: getline
  19         for get chars until buffer is full
  20         if last char is newline add to end of buffer
  21         terminate buffer with '\0'
  22
  23
  24 function: main
  25         while getline > 0
  26                 disgard new line
  27                 reverse line
  28                 print line
  29
  30
  31
  32 */
  33
  34 #include <stdio.h>
  35
  36 #define MAXLEN 1024
  37
  38
  39 /*
  40
  41 loop throguh buffer
  42 convert newlines into nulls marking end of array
  43
  44 */
  45 int discard(char buffer[])
  46 {
  47         int i;
  48         for(i = 0; buffer[i] != '\0'; i++) /* loop until we find NULL */
  49         {
  50                 if(buffer[i] == '\n') { buffer[i] = '\0'; } /* convert newlines into NULL */
  51         }
  52 }
  53
  54 /*
  55
  56 reverse
  57
  58 loop through buffer reversing chars
  59
  60 */
  61 int reverse(char buffer[])
  62 {
  63         char ch;
  64         int i,j;
  65         for(j = 0; buffer[j] != '\0'; ++j) { } /* find length of buffer */
  66         --j; /* move back one space */
  67
  68         /* loop though length of array reversing front to back chars */
  69         for(i = 0; i < j; i++)
  70         {
  71                 ch = buffer[i];
  72                 buffer[i] = buffer[j];
  73                 buffer[j] = ch;
  74                 --j;
  75         }
  76 }
  77
  78 /*
  79
  80 getine
  81
  82 get input passed to program and store in buffer
  83 check along the way that the input has not run out
  84 do this until we reach a newline and then terminate with NULL
  85
  86 */
  87 int getline(char buffer[], int limit)
  88 {
  89         int i;
  90         char c;
  91         for(i = 0; i < limit - 1 && (c = getchar()) != EOF && c != '\n';  ++i)
  92         {
  93                 buffer[i] = c;
  94         }
  95
  96         if(c == '\n') { buffer[i++] = c; }
  97
  98         buffer[i] = '\0'; /* terminate string at this position */
  99
 100         return i; /* return number of chars found in this line */
 101 }
 102
 103 int main()
 104 {
 105         char buffer[MAXLEN];
 106
 107         while(getline(buffer, sizeof buffer) > 0)
 108         {
 109                 // printf("getline\n");
 110                 discard(buffer);
 111                 reverse(buffer);
 112                 printf("%s\n", buffer);
 113         }
 114         return 0;
 115 }