C Segmentation fault in simple (?) program

[matmatmat]

I have a simple c program to play rock paper scissors:


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

int main (int argc, char *argv[])
{
/* Simple "srand()" seed: just use "time()" */
unsigned int iseed = (unsigned int)time(NULL);
srand (iseed);
int ai;
int p = 1000;
while (p != 0){
printf("0) Quit\n1) Rock\n2) Paper\n3)Scissors\n");
scanf("%d", p);
ai = rand() % 3;
if (ai == 1){
if (p == 1){
printf("AI: Rock\n");
printf("Draw!\n");
}
else if (p == 2){
printf("AI: Rock\n");
printf("You win!\n");
}
else if (p == 3){
printf("AI Rock\n");
printf("You lose!\n");
}
}
else if (ai == 2){
if (p == 1){
printf("AI: Paper\n");
printf("You lose!\n");
}
else if (p == 2){
printf("AI: Paper\n");
printf("Draw!\n");
}
else if (p == 3){
printf("AI: Paper\n");
printf("You win\n");
}
}
else{
if (p == 1){
printf("AI: Scissors\n");
printf("You win\n");
}
else if (p == 2){
printf("AI: Scissors\n");
printf("You lose\n");
}
else if (p == 3){
printf("AI: Scissors\n");
printf("Draw!\n");
}
}
}
return 0;
}

it gives a Segmentation fault, I think it's the loop or the random number?

[PmDematagoda]

Compiling the application using the -Wall argument of GCC gives the problem:-

rocks.c: In function ‘main’:
rocks.c:14: warning: format ‘%d’ expects type ‘int *’, but argument 2 has type ‘int’

scanf() requires a pointer to variable p, what you are doing is giving it the value 1000, which is invalid and is the reason for the segmentation fault.

[matmatmat]

Do i make a pointer to p?


int * pointp = p;

[PmDematagoda]

Do i make a pointer to p?


int * pointp = p;


That is still wrong, you are assigning the pointer the memory address of 1000(which is just the value of p), which would still cause a segfault, haven't you used the & operator which gives the memory address of a particular variable/pointer?

What the scanf statement should be is this:-

scanf("%d", &p);

[matmatmat]

Thanks

[bostonaholic]

use

scanf("%d", &p);

This way scanf will pass the memory address of p. Before, you were telling scanf to use the memory address of the value of p--which is incorrect.