RosettaCodeData/Task/Substitution-cipher/C/substitution-cipher.c

65 lines
1.5 KiB
C

#include<stdlib.h>
#include<stdio.h>
#include<wchar.h>
#define ENCRYPT 0
#define DECRYPT 1
#define ALPHA 33
#define OMEGA 126
int wideStrLen(wchar_t* str){
int i = 0;
while(str[i++]!=00);
return i;
}
void processFile(char* fileName,char plainKey, char cipherKey,int flag){
FILE* inpFile = fopen(fileName,"r");
FILE* outFile;
int i,len, diff = (flag==ENCRYPT)?(int)cipherKey - (int)plainKey:(int)plainKey - (int)cipherKey;
wchar_t str[1000], *outStr;
char* outFileName = (char*)malloc((strlen(fileName)+5)*sizeof(char));
sprintf(outFileName,"%s_%s",fileName,(flag==ENCRYPT)?"ENC":"DEC");
outFile = fopen(outFileName,"w");
while(fgetws(str,1000,inpFile)!=NULL){
len = wideStrLen(str);
outStr = (wchar_t*)malloc((len + 1)*sizeof(wchar_t));
for(i=0;i<len;i++){
if((int)str[i]>=ALPHA && (int)str[i]<=OMEGA && flag == ENCRYPT)
outStr[i] = (wchar_t)((int)str[i]+diff);
else if((int)str[i]-diff>=ALPHA && (int)str[i]-diff<=OMEGA && flag == DECRYPT)
outStr[i] = (wchar_t)((int)str[i]-diff);
else
outStr[i] = str[i];
}
outStr[i]=str[i];
fputws(outStr,outFile);
free(outStr);
}
fclose(inpFile);
fclose(outFile);
}
int main(int argC,char* argV[]){
if(argC!=5)
printf("Usage : %s <file name, plain key, cipher key, action (E)ncrypt or (D)ecrypt>",argV[0]);
else{
processFile(argV[1],argV[2][0],argV[3][0],(argV[4][0]=='E'||argV[4][0]=='e')?ENCRYPT:DECRYPT);
printf("File %s_%s has been written to the same location as input file.",argV[1],(argV[4][0]=='E'||argV[4][0]=='e')?"ENC":"DEC");
}
return 0;
}