如何从 C 程序调用 notepad.exe？

Question

i have written a time table program in c

#include<stdio.h> 
#include<conio.h> 
void main()
{
  int i=0;
  int selection;
  char day[20];
  char sub1[20];
  char sub2[20];
  char sub3[20];
  FILE *fp;
  fp=fopen("aa.txt","w");
  textcolor(5);
  textbackground(3);
  clrscr();
  while(i<3)
  {
    printf("Enter the day ");
    scanf("%s",day);
    printf("Enter the period 12.30-1:30 ");
    scanf("%s",sub1);
    printf("Enter the period 1.35-2.40 ");
    scanf("%s",sub2);
    printf("Enter the period 2.45-3.50 ");
    scanf("%s",sub3);
    fprintf(fp,"\n %s TIMETABLE IS AS FOLLOWS\n",day);
    fprintf(fp,"~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
    fprintf(fp,"|~~~~~~~~~|~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~|~~~~~~~~~~|\n");
    fprintf(fp,"| TIME    | 12.30-1.30    | 1.35-2.40    |2.45-3.50 |\n");
    fprintf(fp,"|~~~~~~~~~|~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~|~~~~~~~~~~|\n");
    fprintf(fp,"| SUBJECT *     %s     * %s  * %s|\n",sub1,sub2,sub3);
    fprintf(fp,"|~~~~~~~~~|~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~|~~~~~~~~~~|\n");
    i++;
  }
  printf(" Time table has been Created in the File aa.txt successfully");
  getch();
}

when i finish the timetable. the time table is created in a.txt file. i want that file to be opened and show me automatically in a notepad. how to program that in c?

Answer 1

Use

system("notepad.exe aa.txt");

Answer 2

Dani already described the easier way (using system ), so I'll just describe the other (more complicated but also more flexible) way to do it using the Windows API . Browsing the API (Overview -> System Services -> Processes and Threads), there's a small example on how to create a process using the CreateProcess() function. In your case:

CreateProcess("notepad.exe",   // Name of program to execute
    "aa.txt",                  // Command line
    NULL,                      // Process handle not inheritable
    NULL,                      // Thread handle not inheritable
    FALSE,                     // Set handle inheritance to FALSE
    0,                         // No creation flags
    NULL,                      // Use parent's environment block
    NULL,                      // Use parent's starting directory 
    &si,                       // Pointer to STARTUPINFO structure
    &pi);                      // Pointer to PROCESS_INFORMATION structure

And then wait for the Notepad process to exit, as described in the example.

Answer 3

Third way: use the ShellExecute shell function telling to the shell to "just open the file" with the default editor:

#include <windows.h>
#include <Shellapi.h>

// ...

if(ShellExecute(
    NULL,     // No parent window for error message boxes/...
    "open",   // Shell action ("verb") to be performed on the file (as opposed to "print", "explore", ...)
    "aa.txt", // File to be opened
    NULL,     // Command-line parameters - not used when opening documents
    NULL,     // Working directory - the current one is used by default
    SW_SHOW   // State of the window of the application being launched - SW_SHOW is the default
    )<=(HINSTANCE)32     // If ShellExecute returns a value <=32 it means that an error has occurred
   )
{
    puts("Cannot open aa.txt with the default editor - ShellExecute failed.");
}

This will open aa.txt with the default editor for txt files.

In my opinion, this is the best solution:

• it respects the user's choice for the editor (unlike CreateProcess , which just opens notepad.exe ); if I set PSPad as the default editor for txt files, it will pop up PSPad and not notepad.

• it doesn't have problems with search paths for the editor (where is notepad.exe ?)

• its behavior is fully defined, unlike the system function, which relies on command.com / cmd.exe , which have subtle differences between Windows versions and don't give you any documented/easy way to check if the operation succeeded;

• it doesn't give you any "false feeling of portability" like the system , that will happily compile on a Linux machine but will simply not work at runtime.