the posted code, when compiled with:
gcc -c -Wall -Wextra -Wconversion -pedantic -std=gnu11
results in the following compiler messages:
gcc -ggdb -Wall -Wextra -Wconversion -pedantic -std=gnu11 -c "untitled.c" (in directory: /home/richard/Documents/forum)
untitled.c: In function ‘main’:
untitled.c:6:15: warning: initialization from incompatible pointer type [-Wincompatible-pointer-types]
int *ip = a;
^
untitled.c:7:26: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘long unsigned int’ [-Wformat=]
printf("sizeof:\np: %d\n(*p+0): %d\n**p: %d\nip: %d\n*ip: %d\n",sizeof p, sizeof (*p+0), sizeof **p, sizeof ip, sizeof *ip);
~^
%ld
untitled.c:7:38: warning: format ‘%d’ expects argument of type ‘int’, but argument 3 has type ‘long unsigned int’ [-Wformat=]
printf("sizeof:\np: %d\n(*p+0): %d\n**p: %d\nip: %d\n*ip: %d\n",sizeof p, sizeof (*p+0), sizeof **p, sizeof ip, sizeof *ip);
~^
%ld
untitled.c:7:47: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘long unsigned int’ [-Wformat=]
printf("sizeof:\np: %d\n(*p+0): %d\n**p: %d\nip: %d\n*ip: %d\n",sizeof p, sizeof (*p+0), sizeof **p, sizeof ip, sizeof *ip);
~^
%ld
untitled.c:7:55: warning: format ‘%d’ expects argument of type ‘int’, but argument 5 has type ‘long unsigned int’ [-Wformat=]
printf("sizeof:\np: %d\n(*p+0): %d\n**p: %d\nip: %d\n*ip: %d\n",sizeof p, sizeof (*p+0), sizeof **p, sizeof ip, sizeof *ip);
~^
%ld
untitled.c:7:64: warning: format ‘%d’ expects argument of type ‘int’, but argument 6 has type ‘long unsigned int’ [-Wformat=]
printf("sizeof:\np: %d\n(*p+0): %d\n**p: %d\nip: %d\n*ip: %d\n",sizeof p, sizeof (*p+0), sizeof **p, sizeof ip, sizeof *ip);
~^
%ld
untitled.c:9:17: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 2 has type ‘int (*)[3]’ [-Wformat=]
printf("p: %x\tp+1: %x\n*p: %x\t*p+1: %x\n**p: %d\nip: %x\n*ip: %d",p,p+1,*p,*p+1,**p,ip,*ip);
~^
untitled.c:9:26: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 3 has type ‘int (*)[3]’ [-Wformat=]
printf("p: %x\tp+1: %x\n*p: %x\t*p+1: %x\n**p: %d\nip: %x\n*ip: %d",p,p+1,*p,*p+1,**p,ip,*ip);
~^ ~~~
untitled.c:9:34: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 4 has type ‘int *’ [-Wformat=]
printf("p: %x\tp+1: %x\n*p: %x\t*p+1: %x\n**p: %d\nip: %x\n*ip: %d",p,p+1,*p,*p+1,**p,ip,*ip);
~^
%ls
untitled.c:9:44: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 5 has type ‘int *’ [-Wformat=]
printf("p: %x\tp+1: %x\n*p: %x\t*p+1: %x\n**p: %d\nip: %x\n*ip: %d",p,p+1,*p,*p+1,**p,ip,*ip);
~^ ~~~~
%ls
untitled.c:9:61: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 7 has type ‘int *’ [-Wformat=]
printf("p: %x\tp+1: %x\n*p: %x\t*p+1: %x\n**p: %d\nip: %x\n*ip: %d",p,p+1,*p,*p+1,**p,ip,*ip);
~^
%ls
Compilation finished successfully.
The compiler finishes up by saying the compilation was successful. That does NOT mean that it is ok to run this code and expect valid results/output.
When you correct the code so it cleanly compiles, then please post a EDIT to your question that contains the modified/corrected code.
gcc -ggdb -Wall -Wextra -Wconversion -pedantic -std=gnu11 -c "untitled.c" (in directory: /home/richard/Documents/forum)
untitled.c: In function ‘main’:
untitled.c:6:15: warning: initialization from incompatible pointer type [-Wincompatible-pointer-types]
int *ip = a;
^
untitled.c:7:26: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘long unsigned int’ [-Wformat=]
printf("sizeof:\np: %d\n(*p+0): %d\n**p: %d\nip: %d\n*ip: %d\n",sizeof p, sizeof (*p+0), sizeof **p, sizeof ip, sizeof *ip);
~^
%ld
untitled.c:7:38: warning: format ‘%d’ expects argument of type ‘int’, but argument 3 has type ‘long unsigned int’ [-Wformat=]
printf("sizeof:\np: %d\n(*p+0): %d\n**p: %d\nip: %d\n*ip: %d\n",sizeof p, sizeof (*p+0), sizeof **p, sizeof ip, sizeof *ip);
~^
%ld
untitled.c:7:47: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘long unsigned int’ [-Wformat=]
printf("sizeof:\np: %d\n(*p+0): %d\n**p: %d\nip: %d\n*ip: %d\n",sizeof p, sizeof (*p+0), sizeof **p, sizeof ip, sizeof *ip);
~^
%ld
untitled.c:7:55: warning: format ‘%d’ expects argument of type ‘int’, but argument 5 has type ‘long unsigned int’ [-Wformat=]
printf("sizeof:\np: %d\n(*p+0): %d\n**p: %d\nip: %d\n*ip: %d\n",sizeof p, sizeof (*p+0), sizeof **p, sizeof ip, sizeof *ip);
~^
%ld
untitled.c:7:64: warning: format ‘%d’ expects argument of type ‘int’, but argument 6 has type ‘long unsigned int’ [-Wformat=]
printf("sizeof:\np: %d\n(*p+0): %d\n**p: %d\nip: %d\n*ip: %d\n",sizeof p, sizeof (*p+0), sizeof **p, sizeof ip, sizeof *ip);
~^
%ld
untitled.c:9:17: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 2 has type ‘int (*)[3]’ [-Wformat=]
printf("p: %x\tp+1: %x\n*p: %x\t*p+1: %x\n**p: %d\nip: %x\n*ip: %d",p,p+1,*p,*p+1,**p,ip,*ip);
~^
untitled.c:9:26: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 3 has type ‘int (*)[3]’ [-Wformat=]
printf("p: %x\tp+1: %x\n*p: %x\t*p+1: %x\n**p: %d\nip: %x\n*ip: %d",p,p+1,*p,*p+1,**p,ip,*ip);
~^ ~~~
untitled.c:9:34: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 4 has type ‘int *’ [-Wformat=]
printf("p: %x\tp+1: %x\n*p: %x\t*p+1: %x\n**p: %d\nip: %x\n*ip: %d",p,p+1,*p,*p+1,**p,ip,*ip);
~^
%ls
untitled.c:9:44: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 5 has type ‘int *’ [-Wformat=]
printf("p: %x\tp+1: %x\n*p: %x\t*p+1: %x\n**p: %d\nip: %x\n*ip: %d",p,p+1,*p,*p+1,**p,ip,*ip);
~^ ~~~~
%ls
untitled.c:9:61: warning: format ‘%x’ expects argument of type ‘unsigned int’, but argument 7 has type ‘int *’ [-Wformat=]
printf("p: %x\tp+1: %x\n*p: %x\t*p+1: %x\n**p: %d\nip: %x\n*ip: %d",p,p+1,*p,*p+1,**p,ip,*ip);
~^
%ls
Compilation finished successfully.