Beginning Mac OS® X Programming

A.6. Chapter 6

A.6.1. Exercise 1 solution

1. Open the Grepper project in Xcode, and make the highlighted changes in the following code to the main.c file:

   #include <stdio.h>
   #include <string.h>
   
   // Global constants
   const int MAX_STRING_LENGTH = 256;
   
   // Main function
   int main (int argc, const char * argv[]) {
   
       // Get string to search for, which is the last argument
       const char *searchString = argv[argc-1];
   
       // Loop over files
       unsigned int fileIndex;
       for ( fileIndex = 1; fileIndex < argc-1; ++fileIndex ) {
           // Get input file path from standard input
           const char *inpPath = argv[fileIndex];
   
           // Open file
           FILE *inpFile;

   inpFile = fopen(inpPath, "r");
   
           // Loop over lines in the input file, until there
           // are none left
           char line[MAX_STRING_LENGTH];
           int lineCount = 0;
           while ( fgets(line, MAX_STRING_LENGTH-1, inpFile) ) {
               ++lineCount;
               if ( strstr(line, searchString) ) {
                   printf("In file %s, line %d:\t%s", inpPath, lineCount, line);
               }
           }
   
           // Close files
           fclose(inpFile);
   
       } // End loop over files
   
       return 0;
   }

2. Select the Grepper executable in the Executables group of the Groups & Files panel on the left of the project window. Choose Get Info from the File menu and select the Arguments tab in the Info window that appears. Using the + button, add arguments to the Arguments table at the top. Add the paths of two or more text files first, and a string to search for as the last argument.

3. Compile and run the program by clicking the Build and Go toolbar item in the main project window.

4. Verify from the results that ...