1 /* Makes a lexicographical comparison between two strings */ 2 /* similar to strcmp() function from <string.h> */ 3 4 #include <stdio.h> 5 6 /* This function calculates the length of given string 7 and returns the lenghth by its name as a size_t */ 8 size_t str_len(const char *str) 9 { 10 if(str == NULL) 11 return 1; 12 13 size_t i; 14 while(str[i++]) 15 ; 16 17 return i; 18 } 19 20 /* This function is equivalent to strcmp() function from 21 <string.h> library */ 22 int str_cmp(const char *str1, const char *str2) 23 { 24 /* In case one of the given strings is NULL returns 1; */ 25 if(str1 == NULL || str2 == NULL) 26 return 1; 27 28 29 char aux1, aux2; 30 int i, j, cmp, str1_len, str2_len; 31 str1_len = str_len(str1); 32 str2_len = str_len(str2); 33 34 /* Assigns the length of the longer string to j; */ 35 j = (str1_len > str2_len) ? str1_len : str2_len; 36 37 /* The for loop itinirate until the longest str ENDs */ 38 for(i = 0, cmp = 0; i < j; i++) { 39 40 aux1 = str1[i]; 41 aux2 = str2[i]; 42 43 /* This statement assigns to cmp the difference between */ 44 /* the two coresponding chars of str1 and str2 */ 45 if(aux1 < aux2) { 46 cmp -= (aux2 - aux1); 47 } else if (aux1 > aux2) { 48 cmp += (aux1 - aux2); 49 } 50 51 } 52 return cmp; 53 } 54 55 56 int main(void) { 57 58 char s1[] = "AB"; 59 char s2[] = "ABC"; 60 61 int i, j; 62 i = str_cmp(s1, s2); 63 64 printf("%d\n", i); 65 66 return 0; 67 }
