Thread: help in explaining the program

Hi,

Iam new to programming. Can anyone explain the following program?

Code:

#include "stdafx.h"

FILE	*fp_dump;

/*----- Layer -----*/
/* layer Record*/
typedef struct {
    USHORT          usCode;         	/*LayerCode*/
    USHORT          usSubCode;          	/*SubCode*/
    USHORT          usBrandCode;      	/*BrandCode*/
    USHORT          usStartY;           	/*Latitude*/
    USHORT          usStartX;           	/*Longitude*/
    UINT                uiAR_DA;            	/*Offset*/
    USHORT          usCellSize;         	/*Cell Size*/
    USHORT          usDS;               	/*Relative offset*/
    USHORT	    usKey;		/*SortKey*/
} stRec_t;

/*Layer*/
typedef struct {
    USHORT          usRecCnt;           /*Number of DataRecord*/
    stRec_t     *pstRec;        /*Layer Record*/
} stLayer_t;


static int iGetLayerFile( char*, stLayer_t* );
static int iCodeSort(const void *, const void * );
static int iWriteLayerFile( char *, stLayer_t * );

/******* Sample main function ********/
int main( int argc, char **argv ) {

	int	 i,j,k,l,m,sMax,dMax;
	int    cnt;

  	SearchFiles_T stSearch;
  	SearchFiles _T stSearchFiles;
  	stLayer_t stILF;

	DIR* dir;
		
	char   acFileName[128],cmd[128];
	char   *temp, *pch;

	char   acILFDir[128];                
	char   acNewILFDir[128];
  	char   dirPath[128];         

	if (argv[1] == NULL || argv[2] == NULL)
	{
	    printf("\n<Usage>\nLayerFileSort source dest\n\n");
	    exit( NG );
	} 

	sMax = strlen(argv[1]);
  	dMax = strlen(argv[2]);
	memcpy(acILFDir, argv[1],sMax+2);
 	memmove(acILFDir+sMax,"/\0",2);
	memcpy(acNewILFDir, argv[2],dMax+2);
  	memmove(acNewILFDir+dMax,"/\0",2);
 
	if ((fp_dump=fopen("LayerFile.txt", "w")) == NULL) {
        		printf( "LogFile Open error\n" );
        		exit( NG );
	}

  	memset(&stFinds, 0, sizeof(SearchFiles_T));

	/*Search ILF directories*/
    	if ((FindFiles(acILFDir, &stFinds)) == NG) {
        		exit( NG );
    	}
    	for (i=0 ; i<stFinds.iFileCnt ; i++) {
		memset(&stFindsFiles, 0, sizeof(SearchFiles _T));
		
		/*Search ILF files*/
		if ((FindFiles(stFinds.pcPathName[i], &stFindsFiles)) == NG) {
	        	exit( NG );
		}
		for (j=0 ; j<stFindsFiles.iFileCnt ; j++) {
	
			printf("%5d: %s\n", i, stFindsFiles.pcPathName[j] );
			
			/*get ILF*/
			if( iGetLayerFile( stFindsFiles.pcPathName[j], &stILF ) != OK ){
				printf("ILF reading error : %s\n",stFindsFiles.pcPathName[j] );
				exit( NG );
			}

			/*sort ILF*/

			qsort(stILF.pstRec,stILF.usRecCnt,sizeof(stRec_t),iCodeSort);

			/*get filename*/
			memcpy( acFileName, acNewILFDir,strlen(acNewILFDir));

			for ( m = (int)strlen ( acNewILFDir ),l = (int)strlen ( acILFDir ); 
				l < (int)strlen( stFindsFiles.pcPathName[j] ); l++, m++ )
				acFileName[m] = stFindsFiles.pcPathName[j][l];

			acFileName[m] = '\0';
		
			temp = (char *)malloc(strlen(acFileName)+1);
			if ( NULL == temp )
			{
				printf ("temp malloc error!");
				exit (NG);
			}

			memcpy(temp,acFileName,strlen(acFileName)+1); 
			pch = (char *)malloc(strlen(acFileName)+1);
			if ( NULL == pch )
		  	{
				printf("pch malloc error!");
				exit (NG);
			}
			memcpy(pch,acFileName,strlen(acFileName)+1);
			pch = strrchr(temp,'/');
			cnt = pch - temp + 1;

			memcpy(dirPath,temp,cnt);
			
			dirPath[cnt] = '\0';

  			dir = opendir(dirPath);
			if (!dir) 
			{
				  sprintf(cmd,"mkdir -m 755 -p %s",dirPath);  
				  printf("Making directory :%s\n",dirPath);  
				/*	  printf("cmd:%s\n",cmd);  */
				  system (cmd);           
			} 
			
			else closedir(dir); 
		 
			/*write ILF(finshed sortting)*/                              
			if( iWriteLayerFile ( acFileName, &stILF ) != OK ){
				printf("ILF writing error : %s\n",acFileName );
				exit( NG );
			}
		
			/*		dump list */
			for ( k = 0; k < stILF.usRecCnt; k++ ){
fprintf(fp_dump, "%s,%d,%d,%d,0x%04x,0x%04x,0x%04x,0x%02x,0x%02x,%d\n",
				stFindsFiles.pcPathName[j],
				stILF.pstRec[k].usCode,
				stILF.pstRec[k].usSubCode,
				stILF.pstRec[k].usBrandCode,
				stILF.pstRec[k].usStartX,
				stILF.pstRec[k].usStartY,
				stILF.pstRec[k].uiAR_DA,
				stILF.pstRec[k].usCellSize,
				stILF.pstRec[k].usDS,
				stILF.pstRec[k].usKey);
			}     

			if(stILF.usRecCnt != 0) free (stILF.pstRec);		
		}
	    FindFree(&stFindsFiles);
	}
    	FindFree(&stFinds);		
	fclose(fp_dump);
 
	free(temp);
	free(pch);
	printf("Done!\n");
 	exit( OK );
}
/*=====================
     FUNCTION     : Get LayerFile
     INPUT        : char*			-FileName
					stLayer_t	-Layer
     RETURN       : OK / NG
=======================*/
static int iGetLayerFile( char *acFileName, stLayer_t *pstILF)
{
	FILE	*fp;
	int	  i,j;
	USHORT	usSortKey[SORT_REC] = {9126,7328,7373,7315,7387,7314,7313,7369,9999,7395,7311,7321};
	
	pstILF->usRecCnt = 0;

	if ((fp=fopen(acFileName, "rb")) == NULL) {
		return ( NG );
	}
	fread(&pstILF->usRecCnt, 2, 1, fp);  
    	if( pstILF->usRecCnt != 0 ){
        	pstILF->pstRec =
                (stRec_t*)calloc(pstILF->usRecCnt,sizeof(stRec_t) );
	}

	for( i = 0; i < (int)pstILF->usRecCnt; i++ ){
		fread(&pstILF->pstRec[i].usCode, 2, 1, fp);			/* Layer Code*/
		fread(&pstILF->pstRec[i].usSubCode, 2, 1, fp);		/* Sub Code*/
		fread(&pstILF->pstRec[i].usBrandCode, 2, 1, fp);		/* Brand Code*/

		fread(&pstILF->pstRec[i].usStartY, 2, 1, fp);		/* Lat*/
		fread(&pstILF->pstRec[i].usStartX, 2, 1, fp);		/* Long*/
		fread(&pstILF->pstRec[i].uiAR_DA, 4, 1, fp);		/* Offset*/
		fread(&pstILF->pstRec[i].usCellSize, 2, 1, fp);		/* CellSize*/
		fread(&pstILF->pstRec[i].usDS, 2, 1, fp);			/* RelativeOffset*/

		pstILF->pstRec[i].usKey = 0;					/* Sort Key */
		for ( j = 0; j < SORT_REC; j++ ){
			if( pstILF->pstRec[i].usCode == usSortKey[j] ){
				pstILF->pstRec[i].usKey = j + 1;		/* Sort Key*/
				break;
			}
		}
	}
  
	fclose( fp );

	return( OK );
}
/*=====================
     FUNCTION     : Write LayerFile
     INPUT        : char*			-FileName
					stLayer_t	-Layer
     RETURN       : OK / NG
=======================*/
static int iWriteLayerFile( char *acFileName, stLayer_t *pstILF)
{
	FILE	*fp;
	int		i;
	
	if ((fp=fopen(acFileName, "wb")) == NULL) {
		return ( NG );
	}
	fwrite(&pstILF->usRecCnt, 2, 1, fp);  	
	for( i = 0; i < (int)pstILF->usRecCnt; i++ ){
		fwrite(&pstILF->pstRec[i].usCode, 2, 1, fp);			/* Layer Code*/
		fwrite(&pstILF->pstRec[i].usSubCode, 2, 1, fp);		/* Sub Code*/
		fwrite(&pstILF->pstRec[i].usBrandCode, 2, 1, fp);		/* Brand Code*/
		fwrite(&pstILF->pstRec[i].usStartY, 2, 1, fp);		/* Lat*/
		fwrite(&pstILF->pstRec[i].usStartX, 2, 1, fp);		/* Long*/
		fwrite(&pstILF->pstRec[i].uiAR_DA, 4, 1, fp);		/* Offset*/
		fwrite(&pstILF->pstRec[i].usCellSize, 2, 1, fp);		/* CellSize*/
		fwrite(&pstILF->pstRec[i].usDS, 2, 1, fp);			/* RelativeOffset*/
		
	};
	fclose( fp );

	return( OK );
}
/*===================
     FUNCTION     : iCodeSort
     INPUT        : stLayer_t	-Layer
					stLayer_t	-Layer
     RETURN       : OK / NG
====================*/

static int iCodeSort(const void *data1, const void *data2 )
{
	stRec_t     *pst1;
	stRec_t     *pst2;
	int             iDiff;

	pst1 = (stRec_t*)data1;
	pst2 = (stRec_t*)data2;

	iDiff = (int)pst1->usKey - (int)pst2->usKey;

	return( iDiff );
}