c++ - pipe can not read/write all the chars -

i trying send array of char 1 process using pipe, characters passing not of them! part of beginning. code:

int p1[2], p2[2];  int main() {     pipe(p1);      int f1= fork();      if(f1 == 0)      {                char ar[100];         int n = 38;         for(int i=0;i<n;i++)         { ar[i] = 'f'; }         close(p1[0]); //close read         write(p1[1],ar,n+1);      } else if (f1 > 0)      {         wait(null);         int f2 = fork();         if(f2 == 0)          {                char arr2[100];             close(p1[1]); //close write             int m = read(p1[0],arr2,strlen(arr2));             cout << arr2 << " " << m << endl;             }          else if (f2 > 0)          {wait(null);}      }     return 0; } 

you invoke std::strlen() on uninitialized char array, mistake. std::strlen() looks first occurence of null byte in array , returns position. array uninitialized, making first occurence of null byte undefined.

besides, should check return values of library functions (pipe(), read(), write(), fork(), etc.).