despertly need your help

[madeofdata]

I need the code to implement those two functions;
myStrCmp
Compares two strings, returns true if equal and false otherwise
int myStrCmp(char* str1, char* str2)
myStrNCpy
Copies N characters from str2 to Str1
void myStrNCpy(char* str1, char* str2, int n)

please help me

this is the code of the first fucntion ...where is the error?

#include<stdio.h>
#include"myString.h"
int main (){
char* str1;
char* str2; 
char result; 
printf("Enter string1:\n"); 
scanf("%s",str1); 
printf("Enter string2:");
scanf("%s",str2);
result=myStrCmp(str1,str2); 
 if(result==1) 
  printf(" same"); 
 else 
   printf(" different"); 
 } 


int myStrCmp(char* str1, char* str2){
int i; 

if (myStrLen(str1) - myStrLen(str2))

 return(1);

for ( i = 0 ; i < myStrLen(str1) ; i++ ) { 
  if (*(str1+i) - *(str2+i)) 
  return(1); 
      } 

return(0);
}

[Banfa]

You can't use the standard library functions because?

[madeofdata]

because I need to create my own function !!!

[madeofdata]

You can't use the standard library functions because?

I NEED TO CREATE MY OWN function

[newb16]

if (myStrLen(str1) - myStrLen(str2))
....
if (*(str1+i) - *(str2+i))

Why not ( mystrlen(str1)= =mystrlen(str2) ) instead of subtraction?
Why not str1[i] - str2[i] ?
I don't see any errors, can you do it by just looking at the code?
Oh wait you are scanf'ing your input to nowhere.

[madeofdata]

I did not understand where is the error ?? (scanin nowhere ???

[madeofdata]

what should I write in the main function ?

[newb16]

what should I write in the main function ?

google for scanf %s example of usage. Your str1 pointer is pointing to nowhere, when you call scanf, it takes string from input and puts in to nowhere, possibly causing error. As you are reluctant to specify what exactly your error is, this is advice.
ps there is no need of braces () around return value.

[donbock]

I did not understand where is the error ?? (scanin nowhere ???

Look closely at your main function ... where you accept the input strings. The user types in the string "compare". That's eight characters including the terminal NUL. Where are those characters stored?

By the way, it would be immensely easier to help you if you told us what's going wrong with your code.

You don't tell us what myStrLen does, but I assume it traverses the string until it finds the NUL character. myStrCmp calls myStrLen three times, plus it traverses the string locally. That means myStrCmp traverses the string four times if the inputs match. That's pretty inefficient. Can you think of a way to restructure your code so the string is traversed only once?

[madeofdata]

I tried lot of things ; still it gives me an error message ...can someone tell me what I need to do exactly?

[vmpstr]

It would help if you post what messages you are getting...

Maybe you forgot to return 0 in main? Or maybe your version of strcmp return 1 when the strings are not equal, yet the if statement in your main implies that it returns 1 when they are equal?

(and, of course, you don't allocate any memory to your pointers, as mentioned above)...

[madeofdata]

how should I allocate memory to my pointer ?( it may seem dumy but I am a beginner so;;;;)

[madeofdata]

I know that IT is a runtime error ..since there is the compiler do not detect it ...and the message is '' that ;exe has encounter a problem and have to close .....)

[vmpstr]

If you are a beginner, use a character array (like char array[50] instead of char *array).

[madeofdata]

it does not work ..there still a runtime error !!!!!