atoanger

[caroundw5h]

can someone tell me what is wrong with this code.

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

int main()

{

char input[5]; /* uers's input */
int r_input,count,t_num=0;  /* converted intput, counter and tri number */

printf("What number would you like the triangular of? ");
scanf("%d", &input); /* caputre data */
r_input = atoi(input);  /* validate input */

/* calculate triangular number
* which is bascically factorial
* ex: 7 + 6 + 5 + 4 + 3 + 2 + 1
*/

for(count = 0; count <=r_input; count++)
   {
      t_num = t_num + count;
      printf("Count = %d \t T_num = %d\n", count, t_num);

    }

printf("Finished!\n");
system("pause");
return 0;

}

when i run it, it seems the loop stays at 0? what am i doing wrong?

I removed the atoi function and it worked fine

#include <stdio.h>
/* #include <stdlib.h>  */

int main()

{

/* char input[10]; uers's input */

int r_input,count,t_num=0, input;  /* converted intput, counter and tri number */

printf("What number would you like the triangular of?\n");
scanf("%d", &input); /* caputre data */

/* r_input = atoi(input); validate input */

/* calculate triangular number
* which is bascically factorial
* ex: 7 + 6 + 5 + 4 + 3 + 2 + 1
*/

for(count = 0; count <=input; count++)
   {
      t_num = t_num + count;
      printf("Count = %d \t T_num = %d\n", count, t_num);

    }

printf("Finished!\n\a");
system("pause");
return 0;

}

What am i doing wrong?
while i'm at. Is the triangular number not the same thing as a factorial.
Thank you.

[XSquared]

atoi( ) expects a string, and you're passing it an integer.

Also, you need to check scanf's return code, to make sure that the user does input an integer.

>>while i'm at. Is the triangular number not the same thing as a factorial.
Factorials are n(n-1)(n-2)...2(1). Triangular numbers are n + (n-1) + (n-2)+...+2+1.

[swoopy]

>char input[5]; /* uers's input */
>int r_input,count,t_num=0; /* converted intput, counter and tri number */

>printf("What number would you like the triangular of? ");
>scanf("%d", &input); /* caputre data */

Use %s for strings, and lose the &:
scanf("%s", input); /* capture data */

[XSquared]

Whoops. Missed the declaration of input as a char[].

[Dave_Sinkula]

>Use %s for strings:
>scanf("%s", input); /* capture data */

Bad advice when there are better ways to get strings or integers.

• scanf's %s format has the same problem that gets has: it's hard to guarantee that the receiving buffer won't overflow.