Consider the following ANSI-C program.
#include <stdio.h>
int main(){
int *ptr, a, b, c;
a=5; b=11; c=20;
ptr=&a; *ptr=c; ptr=&c;
a=*(&b); c=*ptr-a;
printf("%d",c);
return(0);
}
The output of this program is ____________. (answer in integer)
Note: Assume that the program compiles and runs successfully.
C Program Output: Step-by-Step Execution Analysis
We trace the values of variables $a$, $b$, $c$, and the pointer $ptr$ throughout the program execution.
Initial Variable Values
- $a = 5$
- $b = 11$
- $c = 20$
- $ptr$ is uninitialized.
Pointer Assignments and Dereferencing
- $ptr = &a;$: The pointer $ptr$ now holds the memory address of variable $a$.
- $*ptr = c;$: The value of $c$ (which is 20) is assigned to the memory location pointed to by $ptr$. Since $ptr$ points to $a$, variable $a$ is updated.
- $a$ becomes 20.
- $ptr = &c;$: The pointer $ptr$ now holds the memory address of variable $c$.
- $a = *(&b);$: This expression retrieves the value stored at the memory address of $b$ (which is 11) and assigns it to $a$.
- $a$ becomes 11.
- $c = *ptr - a;$:
- $*ptr$ dereferences $ptr$, which points to $c$. So, $*ptr$ evaluates to the current value of $c$ (20).
- The expression becomes $c = 20 - a$.
- Substituting the current value of $a$ (11), we get $c = 20 - 11$.
- $c$ becomes 9.
Final Output
The $printf("%d", c);$ statement prints the final value of $c$.
- The final value of $c$ is $9$.
Therefore, the program outputs $9$.
Important Questions from Pointer
- What would be the equivalent pointer expression for referring the array element ar[m][n][o]
- Only legal pointer operations:
A. pointer + number $\rightarrow$ pointer
B. pointer - number $\rightarrow$ number
C. pointer + pointer $\rightarrow$ pointer
D. pointer - pointer $\rightarrow$ pointer
E. pointer - pointer $\rightarrow$ number
Choose the most appropriate answer from the options given below: Consider the following C program:
#include <stdio.h>
void stringcopy(char *, char *);
int main(){
char a[30] = "@#Hello World!";
stringcopy(a, a + 2);
printf("%s\n", a);
return 0;
}
void stringcopy(char *s, char *t) {
while(*t)
*s++ = *t++;
}
Which ONE of the following will be the output of the program?Consider the following C program:
#include <stdio.h>
int main(){
int a;
int arr[5] = {30,50,10};
int *ptr;
ptr = & arr[0] + 1;
a = *ptr;
(*ptr)++;
ptr++;
printf("%d", a + (*ptr) + arr[1]);
return 0;
}
The output of the above program is ____________ (Answer in integer)- The following statement in ‘C’
int (*f())[ ];
declares
