strcmp

问题 I wrote a function, Str::Compare , that is basically a strcmp rewritten in another way. While comparing the two function, in a loop repeted 500'000'000 times, strcmp execute too much fast, about x750 times faster. This code was compiled in a C library with -Os parameter active: int Str::Compare(char* String_1, char* String_2) { char TempChar_1, TempChar_2; do { TempChar_1 = *String_1++; TempChar_2 = *String_2++; } while(TempChar_1 && TempChar_1 == TempChar_2); return TempChar_1 - TempChar_2;

问题 I wrote a function, Str::Compare , that is basically a strcmp rewritten in another way. While comparing the two function, in a loop repeted 500'000'000 times, strcmp execute too much fast, about x750 times faster. This code was compiled in a C library with -Os parameter active: int Str::Compare(char* String_1, char* String_2) { char TempChar_1, TempChar_2; do { TempChar_1 = *String_1++; TempChar_2 = *String_2++; } while(TempChar_1 && TempChar_1 == TempChar_2); return TempChar_1 - TempChar_2;

问题 When I run the following code: #include <stdio.h> int main(int argc, char *argv[]) { int p = 0; p = strcmp(NULL,"foo"); return 0; } I get segmentation fault. echo $? says 139. But when I run #include <stdio.h> int main(int argc, char *argv[]) { int p = 0; strcmp(NULL,"foo"); // Note removed assignment return 0; } I don't get any segmentation fault. Could someone please throw some light? Here is my gcc info: > gcc --version gcc (GCC) 3.4.6 20060404 (Red Hat 3.4.6-8) 回答1: You are probably using

问题 In the following program, i am expecting the for loop to stop after 3 elements. But it keeps on going indefinitely and fails later on with a coredump. is malloc() needed for char*[]` would strcmp fail if i memset to 0? . #include<stdio.h> #include<string.h> #include<stdlib.h> int main() { char* str[10]; memset(str,0,10); str[0]=malloc(sizeof(char)*(strlen("Sample")+1)); str[1]=malloc(sizeof(char)*(strlen("Sample")+1)); str[2]=malloc(sizeof(char)*(strlen("Sample")+1)); strcpy(str[0],"Sample");

问题 I can't see what I'm doing wrong. void contains(NODE *head, char *user) { NODE *this = head; while(this != NULL) { strcpy(temp, this->data); // printf("%s\n",user); // printf("%s\n",temp); printf("%d test\n", strlen(user)); printf("%d node\n", strlen(temp));; printf("%d\n",strcmp(temp, user)); if(strcmp(this->data, user) == 0){ printf("Found data %s\n", this->data); } this = this->next; } } And I have this in main (contains is called on the last line): NODE *head; head = malloc(sizeof(NODE));

问题 I found a nice example of how to use strcmp, but it's only working with fgets(), and i need to make it work with scanf. So, here's the code: int main(void) { char fruit[] = "apple\n"; char ans[80]; do { printf ("Guess my favorite fruit? "); scanf ("%s",ans); } while (strcmp (fruit, ans) != 0); puts ("Correct answer!"); return 0; } Even when I write the correct answear ("apple") it stays in the loop and keeps asking me what is the favorite fruit... I'm guessing it has something to do with the

问题 I was assigned by my teacher to write my own strcmp() function in C. I did create my own version of said function, and I was hoping to get some feedback. int CompareTwoStrings ( char *StringOne, char *StringTwo ) { // Evaluates if both strings have the same length. if ( strlen ( StringOne ) != strlen ( StringTwo ) ) { // Given that the strings have an unequal length, it compares between both // lengths. if ( strlen ( StringOne ) < strlen ( StringTwo ) ) { return ( StringOneIsLesser ); } if (

问题 C bothers me with its handling of strings. I have a pseudocode like this in my mind: char *data[20]; char *tmp; int i,j; for(i=0;i<20;i++) { tmp = data[i]; for(j=1;j<20;j++) { if(strcmp(tmp,data[j])) //then except the uniqueness, store them in elsewhere } } But when i coded this the results were bad.(I handled all the memory stuff,little things etc.) The problem is in the second loop obviously :D. But i cannot think any solution. How do i find unique strings in an array. Example input : abc

问题 The following piece of code behaves differently in 32-bit and 64-bit operating systems. char *cat = "v,a"; if (strcmp(cat, ",") == 1) ... The above condition is true in 32-bit but false in 64-bit. I wonder why this is different? Both 32-bit and 64-bit OS are Linux (Fedora). 回答1: The strcmp() function is only defined to return a negative value if argument 1 precedes argument 2, zero if they're identical, or a positive value if argument 1 follows argument 2. There is no guarantee of any sort

问题 I was playing around with strcmp when I noticed this, here is the code: #include <string.h> #include <stdio.h> int main(){ //passing strings directly printf("%d\n", strcmp("ahmad", "fatema")); //passing strings as pointers char *a= "ahmad"; char *b= "fatema"; printf("%d\n",strcmp(a,b)); return 0; } the output is: -1 -5 shouldn't strcmp work the same? Why is it that I am given different value when I pass strings as "ahmad" or as char* a = "ahmad" . When you pass values to a function they are