Week 4 Laboratory — Sample Solutions

  1. match.c 

    // match.c: reads a (sub)string on the command line, and searches
//          for this (sub)string in every string on stdin
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char *argv[]) {
   int retval = EXIT_SUCCESS;
   if (argc == 2) {
      char word[BUFSIZ]; // BUFSIZ is large and is defined in stdio.h
      int found = 0;
      while (scanf("%s", word) != EOF) {      // see comment below
         if (strstr(word, argv[1]) != NULL) { // NULL means no match
            printf("%s\n", word);
            found = 1;
         }
      }
      if (!found) {
         printf("No match found\n");
      }
   } else {
      fprintf(stderr, "Usage: %s string\n", argv[0]);
      retval = EXIT_FAILURE;
   }
   return retval;
}

// undefined behaviour if length of word exceeds BUFSIZ
// it would be better to use fgets(word, BUFSIZE, stdin)

  2. asci.c 

    // asci.c: print the ASCII codes of printable, uppercase, lowercase and digits
//         "Usage: %s [-printable,-upper,-lower,-digit]\n"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#define PRINTABLE	"-printable"
#define UPPER		"-upper"
#define LOWER		"-lower"
#define DIGIT		"-digit"
#define LASTASCII	127
#define FORMAT		8   // insert a \n every FORMAT chars

int main(int argc, char *argv[]) {
   int someError = 1;
   int version = 0;
   int retval;
   if (argc == 1 || strcmp(argv[1], PRINTABLE) == 0) {
      version = 1;
   } else if (strcmp(argv[1], UPPER) == 0) {
      version = 2;
   } else if (strcmp(argv[1], LOWER) == 0) {
      version = 3;
   } else if (strcmp(argv[1], DIGIT) == 0) {
      version = 4;
   }
   if (argc <= 2) {
      int i;
      int count=1;
      for (i=0; i<=LASTASCII; i++) { // we try every code
         if ((version == 1 && isprint(i)) ||
             (version == 2 && isupper(i)) ||
             (version == 3 && islower(i)) ||
             (version == 4 && isdigit(i))) {
               printf("%d %c\t", i, i);
               if (count % FORMAT == 0) {
                  putchar('\n');
               }
               someError = 0;
               count++;
         }
      }
   }
   if (someError) {
      fprintf(stderr, "Usage: %s [-printable,-upper,-lower,-digit]\n", argv[0]);
      retval = EXIT_FAILURE;
   } else {
      putchar('\n');
      retval = EXIT_SUCCESS;
   }
   return retval;
}

  3. matrix.c 

    //matrix.c: a matrix implementation
#include <stdio.h>
#include "matrix.h"

// read matrix values from stdin into "m"
// return 1 if successful, else 0
int readMatrix(Matrix m) {
   int i, j;
   int dataGood = 1;
   for (i=0; i<SIZE && dataGood; i++) {
      for (j=0; j<SIZE && dataGood; j++) {
         if (scanf("%d",&m[i][j]) != 1) {
            dataGood = 0;
         }
      }
   }
   return dataGood;
}

// copy values from "from" to "to"
void copyMatrix(Matrix from, Matrix to) {
   int i, j;
   for (i=0; i<SIZE; i++) {
      for (j=0; j<SIZE; j++) {
         to[i][j] = from[i][j];
      }
   }
}

// compute sum of "a" + "b"; store result in "c"
void addMatrix(Matrix a, Matrix b, Matrix c) {
   int i, j;
   for (i=0; i<SIZE; i++) {
      for (j=0; j<SIZE; j++) {
         c[i][j] = a[i][j] + b[i][j];
      }
   }
}

// are 2 matrices equal?
// return 1 if equal, else 0
int equalMatrix(Matrix a, Matrix b) {
   int i, j;
   int equal = 1; // assume equal
   for (i=0; i<SIZE && equal; i++) {
      for (j=0; j<SIZE && equal; j++) {
         if (a[i][j] != b[i][j]) {
            equal = 0;
         }
      }
   }
   return equal;
}