[Help]always wrong at first time

I always receive wrong result at first time i run my program. When i type Hello Hello Hello, it will dislay Hello Hello Hello and a symbol. But it only appear at the first time.

You can run my code in Dev C to see.

Code:

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

int main()
{
   unsigned int choice, i, j, n, count;
   char c;
   char s1[100], s2[100], *s3;
   while(1){
   do{
       system("cls");
       printf("Choose one of the following options: ");
       printf("\n1. Input a string");
       printf("\n2. Dislay a string");
       printf("\n3. Convert to Upper Case");
       printf("\n4. Check the number of each charactor exists");       
       printf("\n0. Exit");
       printf("\nYour selection (0 -> 4): ");
       scanf("%d", &choice);}
   while(choice<0 || choice>4);
   switch(choice){
                     case 1: fflush(stdin);
                             printf("\nEnter string ended by EOF (Enter -> Ctrl+Z -> Enter) : ");
                             for(i=0; (c=getchar()) != EOF; i++) s1[i]=c;
                             n=i;
                             for(i=0;i<n;i++)
                                if (s1[i]=='\n') 
                                    {
                                       for(j=i;j<n;j++) s1[j]=s1[j+1];
                                       s1[n--]='\0';
                                       i--;
                                    };
                             system("pause");
                             break;
                     case 2: printf("String entered is:");
                             puts(s1);
                             system("pause");
                             break;
                     case 3: strcpy(s2,s1);
                             s3=strupr(s2);
                             printf("String coverted to upper case: ");
                             puts(s3);
                             system("pause");
                             break;
                     case 4: for (i = 0;i<n;i++)
                                if ( (s1[i] >='a' && s1[i] <= 'z') || (s1[i]>='A' && s1[i]<='Z') || (s1[i]>='0' && s1[i]<='9') )
                                {
                                   int count = 1 ;
                                   for (j = i+1;j<n;j++)
                                      if (s1[j] == s1[i])
                                      {
                                         s1[j] = ' ' ;
                                         count++ ;
                                      }
                                   printf("Have %d letter %c in the string\n",count, s1[i]);
                                }
                             system("pause");
                             break;
                     case 0: exit(0);}}
}

Close to this:Similar topic.

Should probably be kept there... That way if you took us seriously, you would know that your code isn't portable. Not everyone is able to test your code on their system because it relies on extensions and/or implementation behavior.

Slight changes in program purpose between the two threads, but the general badness of both programs is there.

Originally Posted by kingofdcp

You can run my code in Dev C to see.

No one will ever give you a job to write code that only runs on Dev C, so if you are in school with the intent of becoming some kind of professional, you should just get over it right now.

It was explained to you before that using fflush(stdin) is improper and will result in undefined behavior. If you want to ignore that advice, why are you asking for more?

Originally Posted by MacGyver

Close to this:Similar topic.

Should probably be kept there... That way if you took us seriously, you would know that your code isn't portable. Not everyone is able to test your code on their system because it relies on extensions and/or implementation behavior.

Slight changes in program purpose between the two threads, but the general badness of both programs is there.

Thk for comment but problem in this code is different. I put fflush(stdin) but the problem does not solved.
Difference is in this code i use puts(s1); to print string intead use for(i=0;i<n;i++) printf("%c", s1[i]); like that code.

Originally Posted by MK27

No one will ever give you a job to write code that only runs on Dev C, so if you are in school with the intent of becoming some kind of professional, you should just get over it right now.

It was explained to you before that using fflush(stdin) is improper and will result in undefined behavior. If you want to ignore that advice, why are you asking for more?

Yap man. I say " run on Dev C" only mean: you can run to see (not only in Dev C,it maybe BC) because my english is not good so i afraid of you can't understand my problem.

I put fflush(stdin) but the problem does not solved.

The problem is, you SHOULDN'T.

Originally Posted by cyberfish

The problem is, you SHOULDN'T.

i removed but not solved yet ! If i still use:

for(i=0;i<n;i++) printf("%c", s1[i]); to print intead use puts(s1) it run without error

As noted fflush(stdin) is undefined behavior since fflush() is used only for output streams.
Stop printing string when its end ie NULL char is reached instead of walking all the way to its last index.

Originally Posted by itCbitC

As noted fflush(stdin) is undefined behavior since fflush() is used only for output streams.
Stop printing string when its end ie NULL char is reached instead of walking all the way to its last index.

so in my case, can't use puts ? if yes, pls tell me how to fix? thks

Which is the one that's not working for you? The for loop or puts().

Originally Posted by itCbitC

Which is the one that's not working for you? The for loop or puts().

as i said. That is puts() in case 2 and case 3. The string is added more 1 symbol at the first time. (only first time). I dont know why that.

1 - Try initializing your arrays at creation time:

Code:

char s1[100] = {0}, s2[100] = {0};

2 - Try checking for \r as well as \n and removing them both. Normally you wouldn't actually see the symbol for \r, but you might consider checking for it as well.


Quzah.