Thread: Can't find where the value changes

Trying to make a sort of username and password program.
It appears to work fine, i printed almost everything that gets stored so as to prove that my functions work.

In the login function, it shows that pTemp->user.password = "ken". but the second time i print it, inside the while loop, in the first if, pTemp->user.password = a garbage value.

I'm stumped as to where it changes.

May anyone tell me where?

Please go over my program for any other corrections and/or logic corrections

Code:

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <string.h>

struct dataTag
{
       char username[10];
       char password[10]; 
};

struct nodeTag
{
        struct dataTag user;
        struct nodeTag *pNext;
};
typedef struct dataTag dataType;
typedef struct nodeTag nodeType;

nodeType *newNode(dataType Src, nodeType *pNext)
{
         nodeType *pTemp;
         pTemp = malloc(sizeof(nodeType));
         pTemp->user = Src;
         pTemp->pNext = pNext;
         return pTemp;
}

void login(nodeType *pFirst, char user[], char pass[])
{
     nodeType *pTemp;
     pTemp = pFirst;
     int error = 1;
     printf("pFirst->user.password = %s, pTemp->user.password = %s\n", pFirst->user.password, pTemp->user.password);
     getch();
    while((pTemp->pNext != NULL) && error==1)
    {
         printf("Now comparing: %s with %s\n", user, pTemp->user.username);
         getch();
         if(strcmp(user, pTemp->user.username) == 0)
         {
            printf("user check successeful!\nNow comparing: %s with %s\n", pass, pTemp->user.password);
            getch();
            if(strcmp(pass, pTemp->user.password) == 0)
            {
               printf("password check successful! loop should exit!\n");
               error = 0;
               printf("error value successfully changed! %d\n", error);
               getch();
            }
         }
         
         pTemp = pTemp->pNext;
    }
    
    if(error != 0)
             printf("FALSE");
    else
             printf("TRUE");
}
main()
{
      dataType nFirst;
      nodeType *pTemp, *pFirst, *pSecond, *pThird, *pFourth;
      
      strcpy(nFirst.username, "pau");
      strcpy(nFirst.password, "ken");
      pFirst = newNode(nFirst, pSecond);
      
      strcpy(nFirst.username, "admin");
      strcpy(nFirst.password, "admin");
      pSecond = newNode(nFirst, pThird);
      
      strcpy(nFirst.username, "student");
      strcpy(nFirst.password, "dlsu1234");
      pThird = newNode(nFirst, pFourth);

      strcpy(nFirst.username, "commat2");
      strcpy(nFirst.password, "math");
      pFourth = newNode(nFirst, pTemp);
     
      printf("%s\n%s\n\n%s\n%s\n\n%s\n%s\n\n%s\n%s\n\n", pFirst->user.username, pFirst->user.password, pSecond->user.username, pSecond->user.password, pThird->user.username, pThird->user.password, pFourth->user.username, pFourth->user.password);
      /*pFirst->pNext = pSecond;
      pSecond->pNext = pThird;
      pThird->pNext = pFourth;
      pTemp=pFirst;*/
     char username[10], password[10];
    
     printf("Username: ");
     gets(username);
     printf("Password: ");
     int i;
     for(i=0;i<10;i++)
     {
        password[i]=getch();
        switch(password[i])
        {
              case 13:  i=10;
                         printf("\n");
                         break;
              case 8:   
                        i-=2;
                         printf("\b \b");
                         break;
              default: printf("*");
        }
     }
     if(strlen(username) == 0)
     {
                 if(password[0] == 13)
                     printf("Complete the form.");
                 else
                     printf("Username missing.");
     }
     else
     {
         if(password[0] == 13)
                     printf("Password missing.");
         else
          login(pFirst, username, password);
     }
      getch();
}

May you teach me how it works? All I see are a bunch of numbers.

Yep, just did. Debugging is easier on Dev C++ than on Pelles C.

Program fixed now, but I still had to manually point each structure to the next