Thread: [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);}}
}

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.