File size: 1,952 Bytes
bff4ec7 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 | #include "../../string.h"
int strcmp(char *s1, char *s2)
/*@ With str1 str2
Require valid_string(str1) && valid_string(str2) &&
string_length(str1) < INT_MAX && string_length(str2) < INT_MAX &&
store_string(s1, str1) * store_string(s2, str2)
Ensure strcmp_result(str1, str2, __return) &&
store_string(s1, str1) * store_string(s2, str2)
*/
{
int i = 0;
/*@ Inv Assert
valid_string(str1) && valid_string(str2) &&
string_length(str1) < INT_MAX && string_length(str2) < INT_MAX &&
0 <= i && i <= string_length(str1) && i <= string_length(str2) &&
s1 == s1@pre && s2 == s2@pre &&
(forall (k: Z), (0 <= k && k < i) =>
Znth(k, c_string(str1), 0) == Znth(k, c_string(str2), 0)) &&
store_string(s1@pre, str1) * store_string(s2@pre, str2)
*/
while (s1[i] != 0 && s1[i] == s2[i]) {
i++;
}
return s1[i] - s2[i];
}
int strncmp(char *s1, char *s2, int n)
/*@ With str1 str2
Require valid_string(str1) && valid_string(str2) &&
0 <= n && n < INT_MAX &&
string_length(str1) < INT_MAX && string_length(str2) < INT_MAX &&
store_string(s1, str1) * store_string(s2, str2)
Ensure strncmp_result(str1, str2, n, __return) &&
store_string(s1, str1) * store_string(s2, str2)
*/
{
int i = 0;
/*@ Inv Assert
valid_string(str1) && valid_string(str2) &&
0 <= n@pre && n@pre < INT_MAX &&
string_length(str1) < INT_MAX && string_length(str2) < INT_MAX &&
0 <= i && i <= n@pre &&
i <= string_length(str1) && i <= string_length(str2) &&
s1 == s1@pre && s2 == s2@pre && n == n@pre &&
(forall (k: Z), (0 <= k && k < i) =>
Znth(k, c_string(str1), 0) == Znth(k, c_string(str2), 0)) &&
store_string(s1@pre, str1) * store_string(s2@pre, str2)
*/
while (i < n && s1[i] != 0 && s1[i] == s2[i]) {
i++;
}
if (i == n) {
return 0;
}
return s1[i] - s2[i];
}
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