C notes

From OriWiki

combine with Python

[1]

executing a shell command

#include <stdio.h>
#include <stdlib.h>
 
int main(void) {
  printf("hi\n"); 
  system("ls"); 
  return 0;
}

char* arr Vs. char arr[]

#include <stdio.h> 

void foo(char p1[], char *p2) {
  printf("parameter strings: p1-%s, p2-%s, sizeof(p1)-%d, sizeof(p2)-%d\n",p1,p2,sizeof(p1),sizeof(p2)); 
  ++p1; ++p2; 
  printf("after ++p1; ++p2: p1-%s, p2-%s, sizeof(p1)-%d, sizeof(p2)-%d\n",p1,p2,sizeof(p1),sizeof(p2)); 
  // p1 and p2 seems to have the same pointer type 
  // int a=p1; //  warning: initialization makes integer from pointer without a cast
}

int main(void) {
  char str[] = {'h','e','l','l','o','\0'};
  printf("str[] as variable: %s, sizeof: %d, address: %p\n",str,sizeof(str),str);
  //++str; //compilation error: str is not considered lvalue 
  foo(str,str); 
  // int a = str;// warning: initialization makes integer from pointer without a cast... hmmm... I wouldn't expect that   
}