CODEWITHSUNDEEP
cstringscanf
programmer dreamer
programmer dreamer

Reputation: 173

Shortening strings in C

I'm trying to shorten a string length to be displayed (printf). For example I ask user to enter a name, then the program will only display back 15 characters of it.

This is snippet of my code:

int score1=0,score2=0,foul1=0,foul2=0,rebound1=0,rebound2=0,assist1=0,assist2=0,missed1=0,missed2=0,choice1,choice2,choice4,choice5=0;
char choice3,home[15]="HOME",away[15]="AWAY";

printf("\t\t\t==================================\n\t\t\t||     NETBALL SCOREKEEPER\t||\n\t\t\t==================================\n\n");

do
{
    printf("Do you want to enter teams' names?\n1-Yes\n2-No\n:>>");
    scanf("%d",&choice1);
    switch(choice1)
        {
        case 1:
            {
                do
                {
                printf("\nPlease enter HOME team's name(max 15 characters including space)\n:>>");
                scanf(" %[^\n]s",&home);
                printf("\nPlease enter AWAY team's name(max 15 characters including space)\n:>>");
                scanf(" %[^\n]s",&away);
                do
                {
                printf("\n\n%s VS %s\n\n1.Confirm\n2.Edit\n:>>",home,away);
                scanf("%d",&choice2);
                if(choice2!=1&&choice2!=2)
                    printf("\n***ERROR. INVALID INPUT***\n\n");
                }
                while (choice2!=1&&choice2!=2);
                }
                while(choice2==2);
                break;
            }
    case 2:
                {
                printf("\nSet up to default:\n%s VS %s\n\n",home,away);
                break;
                }
    default:
        {
        printf("\n***ERROR. INVALID SELECTION***\n\n");
        break;
        }
    }
}

Upvotes: 1

Views: 1153

Answers (2)

chux
chux

Reputation: 154280

Code has input and output issues;

char home[15]="HOME";
...
printf("Do you want to enter teams' names?\n1-Yes\n2-No\n:>>");
scanf("%d",&choice1);
...
printf("\nPlease enter HOME team's name(max 15 characters including space)\n:>>");
scanf(" %[^\n]s",&home);
...

Input1: The 's' in " %[^\n]s" is certainly not needed. 's' is not part of the "%[^\n]" format specifier.

Input2: If "max 15 characters", then home[15] is too small to save 15 char plus the terminating null character '\0'. Should be home[15+1].

Input3: Code does not limit user input to 15, it only request user to limit input. Users are evil - do not trust them to limit input as requested. Using "%15[^\n]"); limits the number of save char to 15.

Input4: Far better to use fgets() for user input. Read user input into a reasonable size buffer and then scan it.

Input5: Coding both scanf() with fgets() is a problem. scanf("%d",&choice1); typically leaves a '\n' in stdin, that fgets() will consume only that.

[Edit] Input6: (@Cool Guy) &home should be home.

Input solution #1: quick, but not robust:

char home[15+1]="HOME";
...
printf("\nPlease enter HOME team's name(max 15 characters including space)\n:>>");
scanf(" %15[^\n]", home);
...

Input solution #2: more robust:

char home[15+1]="HOME";
char buf[50];
...
printf("Do you want to enter teams' names?\n1-Yes\n2-No\n:>>");
fgets(buf, sizeof buf, stdin);
if (sscanf(buf, "%d",&choice1) != 1 || choice2 < 1 || choice2 > 2) {
  printf("\n***ERROR. INVALID INPUT***\n\n");
  break;
}
...
printf("\nPlease enter HOME team's name(max 15 characters including space)\n:>>");
fgets(buf, sizeof buf, stdin);
if (sscanf(buf, " %15[^\n]", home) != 1) {
  Handle_BadNameInput();  // all spaces
}
...

Output:
To print a string with a maximum number of char uses "%.*s"

printf("%.*s", max_Length, str);

More checks could be added:
1. Insure user input does not have additional data on the line.
2. Check for EOF.

Upvotes: 2

Gopi
Gopi

Reputation: 19874

Going by your question Shortening strings in C

You can do it by

char str[20];
fgets(str, sizeof(str), stdin); /* scanf is nasty for reading strings, use fgets instead (see buffer overflow) */
printf("%.ns",str); /* n = number of characters to be printed out */

prints out n characters in the string left aligned.

If string is str = "someString" and you need to print out just 4 characters in it you can do

printf("%10.4s",str);

Where 10 specifies the field length and 4 specifies the number of characters to be printed out.

Upvotes: 1

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