C/C++ Programmer's Guide (G06.27+, H06.03+)

HP C Implementation-Defined Behavior
HP C/C++ Programmer’s Guide for NonStop Systems—429301-010
A-16
G.3.2 Environment
G.3.2 Environment
No library facilities are available to a freestanding program.
In a freestanding environment, program termination is:
•
The program termination phase of execution begins when a program returns from
the function main, calls the exit() library function, or calls the
terminate_program() library function. In each case, the C library flushes all file
buffers, closes all open files, and causes the process to complete with a certain
completion code, depending on what caused the termination.
•
When the process returns from main with no return value, the process stops with a
completion code of 0, normal termination.
•
When a program calls exit() or terminate_program(), the process
completes with normal or abnormal termination depending upon the completion
code assigned to the status or options parameters, respectively.
HP TNS C allows the declaration of up to three parameters to the program's function
main.
int main(int argc, char *argv[], char *env[])
When declaring parameters to the function main, note:
•
The parameters to main are optional; there can be no parameters, argc and argv,
or all three parameters. env alone is not allowed.
•
The identifiers argc, argv, and env are simply the traditional names of the three
parameters to main; any identifiers may be used.
•
The elements of the environment array env point to strings of the form:
param-name=param-value
where param-name is the name of the environment parameter, and param-
value is its value.
These are valid interactive devices:
Parameters Description
argc An integer value specifying the number of elements in the argument
array argv
argv The argument array. Each element (except for the last) points to a
null-terminated string. argv[0] points to the fully qualified name of
the executing program, the executing program name being that used
in the RUN command. Each of the elements argv[1] through
argv[argc-1] points to one command-line argument; argv[argc]
has the pointer value NULL.
env The environment array. Each element (except for the last) points to a
null-terminated string containing the name and value of one
environment parameter. The last element has the pointer value NULL.