Use VeryPDF PDF AcroForms Modifier Library to get and set values to PDF forms

#include <stdlib.h>
#include <string.h>
#include <stdio.h>						/* Use standard Input/Output Console API */

#include "VSLibA.h"						/* Use VeryPDF PDF Library */
#include "VSExcept.h"					/* Use Exceptions API */
#include "VSError.h"					/* Use Errors API */
#include "VSDocA.h"						/* Use PDF Document API */

#include "VSAcroInfoA.h"			  /* Use Acro Objects API */

int main( int argc, char* argv[] )		/* Get PDF filename as first parameter */
{
	PDFLibHandle	PDFLibrary;			/* PDF Library Handle */
	PDFDocHandle	Doc = NULL;			/* PDF Document Handle */

	ppUns32			Index;				  /* Acro Object Index in PDF Document */
	ppUns32			Count;				/* Count of Acro Objects in PDF Document */
	char			*FieldName;	  /* Variable Acro Field's Name */
	ppUns32			NameLen = 0;
	char			*FieldValue;  /* Variable Acro Field's Value */
	ppUns32			ValueLen = 0;
	char			SettingName[ 128 ];	  /* Constant Acro Field's Name */
	char			OutName[ 128 ];
	char			OutValue[ 128 ];
	TPDFAcroType	FieldType;

	ppInt32			OptCount = 0;
	ppInt32			OptIndex;
	char			*OptValue;
	ppUns32			OptLen	= 0;
	ppInt32			ErrorCode;			/* Check Error Code */
	char			ErrBuff[256];

	ppBool			IsUnicode = true;
	const char *TypeNames[] = { "Unknown", "PushButton", "CheckBox", "RadioButton", "EditBox", "ComboBox", "ListBox", "Signature" };
	PDFLibrary = InitPDFLibrary( NULL, NULL ); /* Initialize PDF Library */
	PDFTRY( PDFLibrary )				/* On error keep exception */

	Doc = PDFDocLoadFromFile( PDFLibrary, "C:/AcroFormAPITest.pdf"); /* Load existing PDF file */

#ifdef WINDOWS_PLATFORM
	PDFDocSetAutoLaunch( Doc, true );	/* Launch destination PDF file after work */
#endif
	Count = PDFAcroGetCount( Doc ); /* Check Count of Acro Objects in PDF Document */
	for ( Index = 0; Index < Count; Index++ ) { /* Take each Acro Objects one by one */
		FieldName = PDFAcroGetNameByIndex( Doc, Index, &IsUnicode, &NameLen	 ); /* Get Acro Object's Name */
		FieldValue = PDFAcroGetValueByIndex( Doc, Index, &ValueLen ); /* Get Acro Object's Value */
		strncpy( OutName, FieldName, NameLen );
		OutName[ NameLen ] = '\0';
		strncpy( OutValue, FieldValue, ValueLen );
		OutValue[ ValueLen ] = '\0';
		if ( FieldName || FieldValue ) {	/* If we had any not null option then ... */
			/* Print Name and Value of current Object */
			printf("Field with name '%s' have value '%s' yet.\n", OutName, ValueLen ? OutValue : "Empty" );
			FieldType = PDFAcroGetTypeByIndex( Doc, Index );
			if ( ( FieldType == PDFAcroTypeRadioButton ) || ( FieldType == PDFAcroTypeListBox ) || ( FieldType == PDFAcroTypeComboBox ) ) {
				OptCount = PDFAcroGetOptionCountByIndex( Doc, Index );
				printf( "\tFieldType is %s. Possible options are:\n", TypeNames[ ( int )FieldType ] );
				for ( OptIndex = 0; OptIndex < OptCount; OptIndex++ ) {
					OptValue = PDFAcroGetOptionValueByIndex( Doc, Index, OptIndex, &OptLen );
					strncpy( OutValue, OptValue, OptLen );
					OutValue[ OptLen ] = '\0';
					printf( "\t\t%d -- %s\n", OptIndex, OptLen ? OutValue : "Empty" );
				}
			}
		}
	}
	sprintf( SettingName, "cp" ); /* Intention to change field with name "cp" (Contact Person) */
	Index = PDFAcroGetIndexByName( Doc, SettingName, false );
	PDFAcroSetValueByIndex( Doc, Index, "Ted Thompson" ); /* Set Field "cp" Value
															   as "Ted Thompson"*/

	FieldValue = PDFAcroGetValueByIndex( Doc, Index, &ValueLen ); /* Get Field "cp" Value */
	if ( FieldValue ) { /* If Value of Contact Person Field is not NULL then ...*/
		/* Print Name and Value of Contact Person Field */
		printf("Field with name '%s' have value '%s' now.\n", SettingName, FieldValue );
	}

	sprintf( SettingName, "cn" ); /* Intention to change field with name "cn" (Company Name) */
	Index = PDFAcroGetIndexByName( Doc, SettingName, false );
	PDFAcroSetValueByIndex( Doc, Index, "Thallium Inc." ); /* Set Field "cn" Value as "Thallium Inc."*/
	FieldValue = PDFAcroGetValueByIndex( Doc, Index, &ValueLen ); /* Get Field "cn" Value */
	if ( FieldValue ) { /* If Value of Company Name Field is not NULL then ...*/
		/* Print Name and Value of Company Name Field */
		printf("Field with name '%s' have value '%s' now.\n", SettingName, FieldValue );
	}

	sprintf( SettingName, "dp" ); /* Intention to change field with name "dp" (Department) */
	Index = PDFAcroGetIndexByName( Doc, SettingName, false );
	/* Set Field "dp" Value as "202 Software Department"*/
	PDFAcroSetValueByIndex( Doc, Index, "202 Software Department" );
	FieldValue = PDFAcroGetValueByIndex( Doc, Index, &ValueLen ); /* Get Field "dp" Value */
	if ( FieldValue ) { /* If Value of Department Field is not NULL then ...*/
		/* Print Name and Value of Department Field */
		printf("Field with name '%s' have value '%s' now.\n", SettingName, FieldValue );
	}
	 /* Save destination PDF file  */
	PDFDocSaveToFile( Doc, "C:/AcroFormInfoTest.pdf" );
	PDFFINALLY( PDFLibrary ) /* Do further if haven't PDF Library Exceptions */
	if ( Doc )
		PDFDocClose ( Doc ); /* Close PDF Document and free memory */
	ErrorCode = PDFLASTERROR( PDFLibrary ); /* Check last error, if 0 then finished successfully */
	if ( ErrorCode ){
		VSGetErrorStr( ErrorCode, ErrBuff );
		printf("Error: %s\n", ErrBuff);

	}else {
		printf("Success...\n");
	}
	DonePDFLibrary( &PDFLibrary ); /* Free PDF Library */
	PDFFINALLYEND( PDFLibrary ); /* End of try...end block */
	return ErrorCode;	/* Return Error Code as program result */
}