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  1. #include <stdio.h>
  2. #include <string.h>
  3.  
  4. // Returns position of first pattern match or -1 if not found
  5. // Example: buffer="abcabc", pattern="cab" should return 2
  6. int findPattern(char* buffer, int bufLen, char* pattern, int patLen)
  7. {
  8.  
  9. if(buffer==nullptr || pattern==nullptr || bufLen <= 0 || patLen <=0 || patLen > bufLen)
  10.     return -1;
  11.  
  12.  
  13. int start;
  14. int end;
  15. for( int i = 0; i < bufLen;i++)
  16. {
  17.     //simple 2 loops
  18.     start = i;
  19.     int patternStart = 0;
  20.     while(start < bufLen && buffer[start]==pattern[patternStart])
  21.     {
  22.         start++;
  23.         patternStart++;
  24.         if(patternStart==patLen)
  25.             return i;
  26.  
  27.  
  28.     }
  29.  
  30. }
  31.  
  32. return -1;
  33.  
  34.  
  35. }
  36.  
  37.  
  38.  
  39.  
  40.  
  41.  
  42. int main() {
  43.     // Test Case 1: Basic match
  44.     char buffer1[] = "abcabc";
  45.     char pattern1[] = "cab";
  46.     printf("Test 1: Expected: 2, Got: %d\n", 
  47.            findPattern(buffer1, strlen(buffer1), pattern1, strlen(pattern1)));
  48.  
  49.     // Test Case 2: Pattern at start
  50.     char buffer2[] = "hello world";
  51.     char pattern2[] = "hell";
  52.     printf("Test 2: Expected: 0, Got: %d\n", 
  53.            findPattern(buffer2, strlen(buffer2), pattern2, strlen(pattern2)));
  54.  
  55.     // Test Case 3: Pattern at end
  56.     char buffer3[] = "hello world";
  57.     char pattern3[] = "orld";
  58.     printf("Test 3: Expected: 7, Got: %d\n", 
  59.            findPattern(buffer3, strlen(buffer3), pattern3, strlen(pattern3)));
  60.  
  61.     // Test Case 4: Pattern not found
  62.     char buffer4[] = "hello world";
  63.     char pattern4[] = "xyz";
  64.     printf("Test 4: Expected: -1, Got: %d\n", 
  65.            findPattern(buffer4, strlen(buffer4), pattern4, strlen(pattern4)));
  66.  
  67.     // Test Case 5: Empty buffer
  68.     char buffer5[] = "";
  69.     char pattern5[] = "abc";
  70.     printf("Test 5: Expected: -1, Got: %d\n", 
  71.            findPattern(buffer5, strlen(buffer5), pattern5, strlen(pattern5)));
  72.  
  73.     // Test Case 6: Empty pattern
  74.     char buffer6[] = "hello";
  75.     char pattern6[] = "";
  76.     printf("Test 6: Expected: -1, Got: %d\n", 
  77.            findPattern(buffer6, strlen(buffer6), pattern6, strlen(pattern6)));
  78.  
  79.     // Test Case 7: Pattern longer than buffer
  80.     char buffer7[] = "abc";
  81.     char pattern7[] = "abcd";
  82.     printf("Test 7: Expected: -1, Got: %d\n", 
  83.            findPattern(buffer7, strlen(buffer7), pattern7, strlen(pattern7)));
  84.  
  85.     // Test Case 8: Null inputs
  86.     printf("Test 8: Expected: -1, Got: %d\n", 
  87.            findPattern(NULL, 5, pattern1, strlen(pattern1)));
  88.  
  89.     // Test Case 9: Repeated pattern
  90.     char buffer9[] = "aaaaa";
  91.     char pattern9[] = "aa";
  92.     printf("Test 9: Expected: 0, Got: %d\n", 
  93.            findPattern(buffer9, strlen(buffer9), pattern9, strlen(pattern9)));
  94.  
  95.     // Test Case 10: Single character
  96.     char buffer10[] = "abcabc";
  97.     char pattern10[] = "b";
  98.     printf("Test 10: Expected: 1, Got: %d\n", 
  99.            findPattern(buffer10, strlen(buffer10), pattern10, strlen(pattern10)));
  100.  
  101.     return 0;
  102. }
Success #stdin #stdout 0s 5280KB
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stdin
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Standard input is empty
stdout
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Test 1: Expected: 2, Got: 2
Test 2: Expected: 0, Got: 0
Test 3: Expected: 7, Got: 7
Test 4: Expected: -1, Got: -1
Test 5: Expected: -1, Got: -1
Test 6: Expected: -1, Got: -1
Test 7: Expected: -1, Got: -1
Test 8: Expected: -1, Got: -1
Test 9: Expected: 0, Got: 0
Test 10: Expected: 1, Got: 1
https://ideone.com/ETQa2i
language:
C++ 4.3.2 (gcc-4.3.2)
created:
7 days ago
visibility:
public

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