Adding and Retrieving Variables

 #include <stdio.h>#include <evm/evm.h>int  main(){	EvmEvent_t event;	EvmStatus_t status;	/* When using a primitive function to add a variable to the event, you must first place the value in a union of type	 EvmVarValue_t. The members of the union have the same names as the EVM variable types.*/	EvmVarValue_t varval_1, varval_2;	EvmVarStruct_t varinfo;	EvmString_t progname;	EvmUint16_t exit_code;	EvmItemValue_t itemval_name;		itemval_name.NAME="sys.unix.evm";	EvmEventCreateVa(&event, 		EvmITEM_NAME,itemval_name, EvmITEM_NONE);

	/* Set and retrieve some values using basic set/get functions: */	varval_1.STRING = "my_app";	varval_2.UINT16 = 17;		/* Use EvmVarSet() to add the variables to the event, giving them meaningful names. The final two arguments are set to	 0 unless you are adding an opaque variable or supplying an	 I18N message ID for a string variable. */	EvmVarSet(event,"progname",EvmTYPE_STRING,varval_1,0,0);EvmVarSet(event,"exit_code",EvmTYPE_UINT16,varval_2,0,0);	/* You can retrieve the value of any variable by passing its name to EvmVarGet() function, which copies the value into	 an EvmVarStruct_t structure. The structure also contains	 the name, type, and size of the variable, so you can write	 generic code to handle any type of variable. Retrieving a	 variable does not remove the variable from the event. You	 can retrieve it as many times as you want. The returned	 information always take up space in heap memory, so you	 must use EvmVarRelease() to clean up after using the	 value.*/	status = EvmVarGet(event,"progname",&varinfo);	if (status == EvmERROR_NONE)	{ 		fprintf(stdout,"Program name:%s\n",varinfo.value.STRING);		EvmVarRelease(&varinfo);	}	status = EvmVarGet(event,"exit_code",&varinfo);	if (status == EvmERROR_NONE)	{ 		fprintf(stdout,"Exit code: %d\n",varinfo.value.UINT16);		EvmVarRelease(&varinfo);	}	/* Set and retrieve the same values using convenience functions: */	/* The EvmVarSetString() and EvmVarSetUint16() functions, along with other functions in the EvmVarSetXxx() family, are simpler alternatives to the EvmVarSet() function. They require fewer arguments, and there is no need to set up a value structure. If you want to supply an I18N message-id with a string variable, use the EvmVarSetStringI18N() function */	EvmVarSetString(event,"progname","my_app");	EvmVarSetUint16(event,"exit_code",17);	/* The EvmVarGetString() and EvmVarGetUint16() functions, along with other functions in the EvmVarGetXxx() family, are simpler alternatives to the EvmVarGet() function. They	 require fewer arguments, and there is no need to set up a	 variable information structure or to follow the retrieval	 operation with a call to EvmVarRelease().*/	status = EvmVarGetString(event,"progname",&progname,NULL);		if (status == EvmERROR_NONE)		fprintf(stdout,"Program name: %s\n",progname);	/* If you use a convenience function to retrieve a string or opaque variable, the function allocates heap space for the	 value and returns a pointer to the heap. You must use	 free() to release the heap space after you have finished	 with the value.*/	free(progname);	status = EvmVarGetUint16(event,"exit_code",&exit_code);		if (status == EvmERROR_NONE)	fprintf(stdout,"Exit code: %d\n",exit_code);	/* After you have finished with the event, free the storage space used by the event. */	EvmEventDestroy(event);}