Execute Functions With GDB Call

1. Introduction

The call command in GDB allows you to execute functions, modify variables, and evaluate expressions during debugging. It helps test functions, change program states, and interact with the program dynamically without restarting execution.

2. Lab

2.1. No Argument

  
void print_hello()
{
    printf("hello\n");
}
  
  
(gdb) call print_hello()
hello

2.2. Pass By Value

  
void print_int(int a)
{
    printf("%d\n", a);
}
  
  
(gdb) call print_int(3)
3

2.3. Pass By Reference

  
void print_ref_int(int &a)
{
    printf("%d\n", a);
}
  
  
(gdb) set $ptr = (int*) malloc(sizeof(int))
(gdb) set *$ptr = 3
(gdb) call print_ref_int(*$ptr)
3

2.4. Pass By Pointer

  
void print_pointer_int(int *a)
{
    printf("%d\n", *a);
}
  
  
(gdb) set $ptr = (int*) malloc(sizeof(int))
(gdb) set *$ptr = 3
(gdb) call print_ref_int(*$ptr)
3

References