如何查看 gdb 中二维数组特定索引的元素？

Question

char *str = "Coding";
char arr[5][10];

for (i = 0;i< 5; i++)
{
   for (j = 0; j< 10; j++)
   {
       if (i>=2 && j==0)
            {
                arr[i][j]= first_string[i-2];
            }
    }
}

Now I want to see the element at arr[2][3] .

When I do p arr[2][3] , it gives

Cannot perform pointer math on incomplete types, try casting to a known type, or void *.

Answer 1

Add a line to your program after the for loops

int main(void)
{
    ...
    return 0; // Line 20
}

Compile with -g (debug mode on)

gcc -std=c11 -Wall -g -o demo demo.c

Launch your program with gdb

gdb demo

set a breakpoint at line 20 (the line coresponding to return 0; )

break 20

run the program

run

print the value of the array

print arr[2][3]