uncrypt.c

日文版畅销书籍10天学会C语言的源程序。适合入门者学习使用。希望对大家有帮助。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dir.h>

//僼傽僀儖暅崋壔
main (int argc, char* argv[]) {
	char ch;
	FILE *fp;	//擖椡僼傽僀儖億僀儞僞
	FILE *wfp;	//弌椡僼傽僀儖億僀儞僞
	char filename[256];		//擖椡僼傽僀儖柤
	char outfilename[256];	//弌椡僼傽僀儖柤
	char dirname[] = "crypt";	//弌椡僼傽僀儖嶌惉僨傿儗僋僩儕
	char key[128];	//埫崋僉乕
	int keylen;		//埫崋僉乕偺挿偝
	int i = 0;
	
	//埫崋壔僼傽僀儖柤偺寛掕
	if (argc > 1) {
		strcpy(filename, argv[1]);
	} else {
		printf("僼傽僀儖柤傪擖椡偟偰壓偝偄 > ");
		scanf("%s", filename);
	}

	//埫崋僉乕偺擖椡
	printf("埫崋僉乕傪擖椡偟偰壓偝偄 > ");
	scanf("%s", key);
	keylen = strlen(key);

	//埫崋壔僼傽僀儖乮擖椡僼傽僀儖乯僆乕僾儞
	if((fp = fopen(filename, "rb")) == NULL) {
		printf("僼傽僀儖僆乕僾儞僄儔乕\n");
		exit(1);
	}

	//暅崋壔僼傽僀儖乮弌椡僼傽僀儖乯僆乕僾儞
	mkdir(dirname);
	strcpy(outfilename, dirname);
	strcat(outfilename, "/");
	strcat(outfilename, filename);
	if((wfp = fopen(outfilename, "wb")) == NULL) {
		printf("僼傽僀儖僆乕僾儞僄儔乕\n");
		exit(1);
	}

	//暅崋壔
	while (fread(&ch, sizeof(char), 1, fp) == 1) {
		ch = ch - key[i++];
		if(i >= keylen) { i = 0; }
		fwrite(&ch, sizeof(char), 1, wfp);
	}

	fclose(wfp);
	fclose(fp);
	printf("僼傽僀儖 %s 傪暅崋壔偟傑偟偨\n", filename);
	printf("嶌惉僼傽僀儖丗%s\n", outfilename);

	return 0;
}