Evaluates an expression and, when the result is false, prints a diagnostic message and aborts the program.


void assert(
int expression
);



Parameters:

expression
Expression (including pointers) that evaluates to nonzero or 0.



Example
In this program, the analyze_string function uses the assert function to test several conditions related to string and length. If any of the conditions fails, the program prints a message indicating what caused the failure.


// crt_assert.c
// compile with: /c
#include
#include
#include

void analyze_string( char *string ); // Prototype

int main( void )
{
char test1[] = "abc", *test2 = NULL, test3[] = "";

printf ( "Analyzing string '%s'\n", test1 ); fflush( stdout );
analyze_string( test1 );
printf ( "Analyzing string '%s'\n", test2 ); fflush( stdout );
analyze_string( test2 );
printf ( "Analyzing string '%s'\n", test3 ); fflush( stdout );
analyze_string( test3 );
}

// Tests a string to see if it is NULL,
// empty, or longer than 0 characters.
void analyze_string( char * string )
{
assert( string != NULL ); // Cannot be NULL
assert( *string != '\0' ); // Cannot be empty
assert( strlen( string ) > 2 ); // Length must exceed 2
}

Sample Output

Analyzing string 'abc'
Analyzing string '(null)'
Assertion failed: string != NULL, file crt_assert.c, line 24

This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.


with reference to msdn library......

Evaluates an expression and, when the result is false, prints a diagnostic message and aborts the program.


void assert(
int expression
);



Parameters:

expression
Expression (including pointers) that evaluates to nonzero or 0.

Example program:

In this program, the analyze_string function uses the assert function to test several conditions related to string and length. If any of the conditions fails, the program prints a message indicating what caused the failure.


// crt_assert.c
// compile with: /c
#include
#include
#include

void analyze_string( char *string ); // Prototype

int main( void )
{
char test1[] = "abc", *test2 = NULL, test3[] = "";

printf ( "Analyzing string '%s'\n", test1 ); fflush( stdout );
analyze_string( test1 );
printf ( "Analyzing string '%s'\n", test2 ); fflush( stdout );
analyze_string( test2 );
printf ( "Analyzing string '%s'\n", test3 ); fflush( stdout );
analyze_string( test3 );
}

// Tests a string to see if it is NULL,
// empty, or longer than 0 characters.
void analyze_string( char * string )
{
assert( string != NULL ); // Cannot be NULL
assert( *string != '\0' ); // Cannot be empty
assert( strlen( string ) > 2 ); // Length must exceed 2
}


Sample Output

Analyzing string 'abc'
Analyzing string '(null)'
Assertion failed: string != NULL, file crt_assert.c, line 24

This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.