⑴ c语言英文文本加密
#include "stdio.h"
#include <stdlib.h>
int main(int argc,char *argv[]){
FILE *fp,*fq;
int k,t;
fp=fopen("AAA12345678901.txt","w+");
if(!fp || (fq=fopen("tmp.txt","w"))==NULL){
printf("Failed to open the file and exit... ");
return 0;
}
printf("Please enter a short passage(letters+space+punctuation,'Enter' end)... ");
while((t=getchar())!=' ')//为文件输入内容
fputc(t,fp);
printf("Please enter the encryption key(int >0)... k=");
while(scanf("%d",&k)!=1 || k<1){//输入加密密钥并判断是否正确
printf("Input error, redo: ");
fflush(stdin);
}
rewind(fp);
while(t=fgetc(fp),!feof(fp))//加密
if(t>='A' && t<='Z')
fputc(((t-'A')+k)%26+'A',fq);
else if(t>='a' && t<='z')
fputc(((t-'a')+k)%26+'a',fq);
else
fputc(t,fq);
fclose(fp);//关闭原文件
fclose(fq);//关闭加密后的文件
remove("AAA12345678901.txt");//删除原文件
rename("tmp.txt","AAA12345678901.txt");//将加密后的文件更换为原文件名
printf(" ");
if(fp=fopen("AAA12345678901.txt","r")){
while((t=fgetc(fp))!=EOF)
printf("%c",t);
printf(" Encryption success! ");
}
else
printf(" Failed to open the encrypted file... ");
fclose(fp);
return 0;
}
代码格式和运行样例图片：
⑵ 求c语言下获取一个字符串MD5值得函数
1. md5.h：
＃pragma once
typedef unsigned long int UINT32;
typedef unsigned short int UINT16;
/× MD5 context. */
typedef struct {
UINT32 state[4]; /× state (ABCD) */
UINT32 count[2]; /× number of bits, molo 2^64 (lsb first) */
unsigned char buffer[64]; /× input buffer */
} MD5_CTX;
void MD5Init (MD5_CTX *);
void MD5Update (MD5_CTX *, unsigned char *, unsigned int);
void MD5Final (unsigned char [16], MD5_CTX *);
——————————————————————————
2. md5.cpp：
＃include "md5.h"
＃include "memory.h"
＃define S11 7
＃define S12 12
＃define S13 17
＃define S14 22
＃define S21 5
＃define S22 9
＃define S23 14
＃define S24 20
＃define S31 4
＃define S32 11
＃define S33 16
＃define S34 23
＃define S41 6
＃define S42 10
＃define S43 15
＃define S44 21
static void MD5Transform (UINT32 a[4], unsigned char b[64]);
static void Encode (unsigned char *, UINT32 *, unsigned int);
static void Decode (UINT32 *, unsigned char *, unsigned int);
static unsigned char PADDING[64] = {
0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
＃define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
＃define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
＃define H(x, y, z) ((x) ^ (y) ^ (z))
＃define I(x, y, z) ((y) ^ ((x) | (~z)))
＃define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
＃define FF(a, b, c, d, x, s, ac) {
(a) += F ((b), (c), (d)) + (x) + (UINT32)(ac);
(a) = ROTATE_LEFT ((a), (s));
(a) += (b);
}
＃define GG(a, b, c, d, x, s, ac) {
(a) += G ((b), (c), (d)) + (x) + (UINT32)(ac);
(a) = ROTATE_LEFT ((a), (s));
(a) += (b);
}
＃define HH(a, b, c, d, x, s, ac) {
(a) += H ((b), (c), (d)) + (x) + (UINT32)(ac);
(a) = ROTATE_LEFT ((a), (s));
(a) += (b);
}
＃define II(a, b, c, d, x, s, ac) {
(a) += I ((b), (c), (d)) + (x) + (UINT32)(ac);
(a) = ROTATE_LEFT ((a), (s));
(a) += (b);
}
void MD5Init (MD5_CTX *context)
{
context->count[0] = context->count[1] = 0;
context->state[0] = 0x67452301;
context->state[1] = 0xefcdab89;
context->state[2] = 0x98badcfe;
context->state[3] = 0x10325476;
}
void MD5Update (MD5_CTX *context, unsigned char *input, unsigned int inputLen)
{
unsigned int i, index, partLen;
index = (unsigned int)((context->count[0] >> 3) & 0x3F);
if ((context->count[0] += ((UINT32)inputLen << 3))
< ((UINT32)inputLen << 3))
context->count[1]++;
context->count[1] += ((UINT32)inputLen >> 29);
partLen = 64 - index;
if (inputLen >= partLen) {
memcpy((unsigned char *)&context->buffer[index], (unsigned char *)input, partLen);
MD5Transform (context->state, context->buffer);
for (i = partLen; i + 63 < inputLen; i += 64)
MD5Transform (context->state, &input[i]);
index = 0;
}
else
i = 0;
memcpy((unsigned char *)&context->buffer[index], (unsigned char *)&input[i],
inputLen-i);
}
void MD5Final (unsigned char digest[16], MD5_CTX * context)
{
unsigned char bits[8];
unsigned int index, padLen;
Encode (bits, context->count, 8);
index = (unsigned int)((context->count[0] >> 3) & 0x3f);
padLen = (index < 56) ? (56 - index) : (120 - index);
MD5Update (context, PADDING, padLen);
MD5Update (context, bits, 8);
Encode (digest, context->state, 16);
memset ((unsigned char *)context, 0, sizeof (*context));
}
static void MD5Transform (UINT32 state[4], unsigned char block[64])
{
UINT32 a = state[0], b = state[1], c = state[2], d = state[3], x[16];
Decode (x, block, 64);
/× Round 1 */
FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /× 1 */
FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /× 2 */
FF (c, d, a, b, x[ 2], S13, 0x242070db); /× 3 */
FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /× 4 */
FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /× 5 */
FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /× 6 */
FF (c, d, a, b, x[ 6], S13, 0xa8304613); /× 7 */
FF (b, c, d, a, x[ 7], S14, 0xfd469501); /× 8 */
FF (a, b, c, d, x[ 8], S11, 0x698098d8); /× 9 */
FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /× 10 */
FF (c, d, a, b, x[10], S13, 0xffff5bb1); /× 11 */
FF (b, c, d, a, x[11], S14, 0x895cd7be); /× 12 */
FF (a, b, c, d, x[12], S11, 0x6b901122); /× 13 */
FF (d, a, b, c, x[13], S12, 0xfd987193); /× 14 */
FF (c, d, a, b, x[14], S13, 0xa679438e); /× 15 */
FF (b, c, d, a, x[15], S14, 0x49b40821); /× 16 */
/× Round 2 */
GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /× 17 */
GG (d, a, b, c, x[ 6], S22, 0xc040b340); /× 18 */
GG (c, d, a, b, x[11], S23, 0x265e5a51); /× 19 */
GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /× 20 */
GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /× 21 */
GG (d, a, b, c, x[10], S22, 0x2441453); /× 22 */
GG (c, d, a, b, x[15], S23, 0xd8a1e681); /× 23 */
GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /× 24 */
GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /× 25 */
GG (d, a, b, c, x[14], S22, 0xc33707d6); /× 26 */
GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /× 27 */
GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /× 28 */
GG (a, b, c, d, x[13], S21, 0xa9e3e905); /× 29 */
GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /× 30 */
GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /× 31 */
GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /× 32 */
/× Round 3 */
HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /× 33 */
HH (d, a, b, c, x[ 8], S32, 0x8771f681); /× 34 */
HH (c, d, a, b, x[11], S33, 0x6d9d6122); /× 35 */
HH (b, c, d, a, x[14], S34, 0xfde5380c); /× 36 */
HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /× 37 */
HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /× 38 */
HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /× 39 */
HH (b, c, d, a, x[10], S34, 0xbebfbc70); /× 40 */
HH (a, b, c, d, x[13], S31, 0x289b7ec6); /× 41 */
HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /× 42 */
HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /× 43 */
HH (b, c, d, a, x[ 6], S34, 0x4881d05); /× 44 */
HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /× 45 */
HH (d, a, b, c, x[12], S32, 0xe6db99e5); /× 46 */
HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /× 47 */
HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /× 48 */
/× Round 4 */
II (a, b, c, d, x[ 0], S41, 0xf4292244); /× 49 */
II (d, a, b, c, x[ 7], S42, 0x432aff97); /× 50 */
II (c, d, a, b, x[14], S43, 0xab9423a7); /× 51 */
II (b, c, d, a, x[ 5], S44, 0xfc93a039); /× 52 */
II (a, b, c, d, x[12], S41, 0x655b59c3); /× 53 */
II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /× 54 */
II (c, d, a, b, x[10], S43, 0xffeff47d); /× 55 */
II (b, c, d, a, x[ 1], S44, 0x85845dd1); /× 56 */
II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /× 57 */
II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /× 58 */
II (c, d, a, b, x[ 6], S43, 0xa3014314); /× 59 */
II (b, c, d, a, x[13], S44, 0x4e0811a1); /× 60 */
II (a, b, c, d, x[ 4], S41, 0xf7537e82); /× 61 */
II (d, a, b, c, x[11], S42, 0xbd3af235); /× 62 */
II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /× 63 */
II (b, c, d, a, x[ 9], S44, 0xeb86d391); /× 64 */
state[0] += a;
state[1] += b;
state[2] += c;
state[3] += d;
memset ((unsigned char *)x, 0, sizeof (x));
}
static void Encode (unsigned char *output, UINT32 *input, unsigned int len)
{
unsigned int i, j;
for (i = 0, j = 0; j < len; i++, j += 4) {
output[j] = (unsigned char)(input[i] & 0xff);
output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
}
}
static void Decode (UINT32 *output, unsigned char *input, unsigned int len)
{
unsigned int i, j;
for (i = 0, j = 0; j < len; i++, j += 4)
output[i] = ((UINT32)input[j]) | (((UINT32)input[j+1]) << 8) |
(((UINT32)input[j+2]) << 16) | (((UINT32)input[j+3]) << 24);
}
——————————————————————————
＃include <stdio.h>
＃include <string.h>
＃include "md5.h"
int main ()
{
char tmp[128];
unsigned char digest[16];
MD5_CTX context;
scanf("%s",tmp);
MD5Init (&context);
MD5Update (&context, (unsigned char*)tmp, strlen(tmp));
MD5Final (digest,&context);
printf("MD5Value:");
for(int i=0; i<16; ++i)
{
printf("%02X",digest[i]);
}
printf(" ");
return 0;
}
⑶ c语言编写加密程序
#include <stdio.h>
#include <string.h>
#include "global.h"
#include "md5.h"
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21
static void MD5Transform PROTO_LIST ((UINT4 [4], unsigned char
[64]));
static void Encode PROTO_LIST
((unsigned char *, UINT4 *, unsigned int));
static void Decode PROTO_LIST
((UINT4 *, unsigned char *, unsigned int));
static void MD5_memcpy PROTO_LIST ((POINTER, POINTER, unsigned
int));
static void MD5_memset PROTO_LIST ((POINTER, int, unsigned int));
static unsigned char PADDING[64] = {
0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
#define FF(a, b, c, d, x, s, ac) { (a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); (a) = ROTATE_LEFT ((a), (s)); (a) += (b);}
#define GG(a, b, c, d, x, s, ac) { \
(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
}
#define HH(a, b, c, d, x, s, ac) { \
(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
}
#define II(a, b, c, d, x, s, ac) { \
(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
}
void MD5Init (context)
MD5_CTX *context;
{
context->count[0] = context->count[1] = 0;
context->state[0] = 0x67452301;
context->state[1] = 0xefcdab89;
context->state[2] = 0x98badcfe;
context->state[3] = 0x10325476;
}
void MD5Update (context, input, inputLen)
MD5_CTX *context;
unsigned char *input;
unsigned int inputLen;
{
unsigned int i, index, partLen;
index = (unsigned int)((context->count[0] >> 3) & 0x3F);
if ((context->count[0] += ((UINT4)inputLen << 3))< ((UINT4)inputLen << 3))
context->count[1]++;
context->count[1] += ((UINT4)inputLen >> 29);
partLen = 64 - index;
if (inputLen >= partLen)
{
MD5_memcpy((POINTER)&context->buffer[index], (POINTER)input, partLen);
MD5Transform (context->state, context->buffer);
for (i = partLen; i + 63 < inputLen; i += 64)
MD5Transform (context->state, &input[i]);
index = 0;
}
else
i = 0;
MD5_memcpy((POINTER)&context->buffer[index], (POINTER)&input[i],inputLen-i);
}
void MD5Final (digest, context)
unsigned char digest[16];
MD5_CTX *context;
{
unsigned char bits[8];
unsigned int index, padLen;
Encode (bits, context->count, 8);
index = (unsigned int)((context->count[0] >> 3) & 0x3f);
padLen = (index < 56) ? (56 - index) : (120 - index);
MD5Update (context, PADDING, padLen);
MD5Update (context, bits, 8);
Encode (digest, context->state, 16);
MD5_memset ((POINTER)context, 0, sizeof (*context));
}
static void MD5Transform (UINT4 state[4], unsigned char block[64])
{
UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];
Decode (x, block, 64);
FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */
FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */
FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */
FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */
FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */
FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */
FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */
FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */
FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */
FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */
FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */
/* Round 2 */
GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */
GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */
GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */
GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */
GG (d, a, b, c, x[10], S22, 0x2441453); /* 22 */
GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */
GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */
GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */
GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */
GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */
GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */
GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */
/* Round 3 */
HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */
HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */
HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */
HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */
HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */
HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */
HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */
HH (b, c, d, a, x[ 6], S34, 0x4881d05); /* 44 */
HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */
HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */
/* Round 4 */
II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */
II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */
II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */
II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */
II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */
II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */
II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */
state[0] += a;
state[1] += b;
state[2] += c;
state[3] += d;
MD5_memset ((POINTER)x, 0, sizeof (x));
}
static void Encode (output, input, len)
unsigned char *output;
UINT4 *input;
unsigned int len;
{
unsigned int i, j;
for (i = 0, j = 0; j < len; i++, j += 4)
{
output[j] = (unsigned char)(input[i] & 0xff);
output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
}
}
static void Decode (output, input, len)
UINT4 *output;
unsigned char *input;
unsigned int len;
{
unsigned int i, j;
for (i = 0, j = 0; j < len; i++, j += 4)
output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) << 8) |(((UINT4)input[j+2]) << 16) | (((UINT4)input[j+3]) << 24);
}
static void MD5_memcpy (output, input, len)
POINTER output;
POINTER input;
unsigned int len;
{
unsigned int i;
for (i = 0; i < len; i++)
output[i] = input[i];
}
static void MD5_memset (output, value, len)
POINTER output;
int value;
unsigned int len;
{
unsigned int i;
for (i = 0; i < len; i++)
((char *)output)[i] = (char)value;
}
#ifndef MD
#define MD 5
#endif
#define TEST_BLOCK_LEN 1000
#define TEST_BLOCK_COUNT 1000
static void MDString PROTO_LIST ((char *));
static void MDPrint PROTO_LIST ((unsigned char [16]));
#define MD_CTX MD5_CTX
#define MDInit MD5Init
#define MDUpdate MD5Update
#define MDFinal MD5Final
int main (int argc, char *argv[])
{
int i;
if (argc > 1)
{ MDString(argv[1]);
return (0);
}
}
static void MDString (char *string)
{
MD_CTX context;
unsigned char digest[16];
unsigned int len = strlen (string);
MDInit (&context);
MDUpdate (&context, string, len);
MDFinal (digest, &context);
printf ("MD%d (\"%s\") = ", MD, string);
MDPrint (digest);
printf ("\n");
}
static void MDPrint (unsigned char digest[16])
{
unsigned int i;
for (i = 0; i < 16; i++)
printf ("%02x", digest[i]);
}
⑷ c语言编程 为了使电文保密，往往按一定规律将其转换成密码，收报人再按约定的规律将其译回原文。
#include <stdio.h>
void main()
{
char context[256];
int i=0;//context数组的下标
printf("Type the original text:\n");
gets(context);
while(context[i]!='!'&&context[i]!=0)//如果原字符串忘加“！”也应能正常结束
{
if ((context[i]>='A'&&context[i]<='V')||(context[i]>='a'&&context[i]<='v'))
context[i]=context[i]+4;
else if ((context[i]>='W'&&context[i]<='Z')||(context[i]>='w'&&context[i]<='z'))
context[i]=context[i]-22;
i++;
}
puts(context);
getchar();
}
⑸ context->count[0]=0; c语言 什么意思
context是一个结构体类型的变量；
这个结构体里面声明了一个名为count的数组（可能是指针，类型为整形(暂无法准确判断)）。
这个句子把context结构体变量的count数组的第一个数赋值为0
⑹ 用C语言编写一个排列组合的程序
#include<stdio.h>
int a[5];
int len1,len2,len3;
void input(int len1,int len2,int len3)
{
printf("%d %d %d\n",a[len1],a[len2],a[len3]);
}
void solve(int len1,int len2,int len3)
{
input(len1,len2,len3);
if(len1==2) return;
if(len3<4) len3++;
else if(len2<3)
{
len2++;
len3=len2+1;
}
else if(len1<2)
{
len1++;
len2=len1+1;
len3=len2+1;
}
solve(len1,len2,len3);
}
void main()
{
int i;
for(i=0;i<5;i++) a[i]=i+1;
printf("所构成组合是:\n");
solve(0,1,2);
return ;
}