#ifndef MD5_H
#define MD5_H
typedef struct {
unsigned int count[2];
unsigned int state[4];
unsigned char buffer[64];
}MD5_CTX;
#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 + ac;a = ROTATE_LEFT(a,s); a += b; }
#define GG(a,b,c,d,x,s,ac) {a += G(b,c,d) + x + ac; a = ROTATE_LEFT(a,s);a += b; }
#define HH(a,b,c,d,x,s,ac) { a += H(b,c,d) + x +ac;a = ROTATE_LEFT(a,s); a += b; }
#define II(a,b,c,d,x,s,ac) {a += I(b,c,d) + x + ac;a = ROTATE_LEFT(a,s);a += b; }
void MD5Init(MD5_CTX *context);
void MD5Update(MD5_CTX *context,unsigned char *input,unsigned int inputlen);
void MD5Final(MD5_CTX *context,unsigned char digest[16]);
void MD5Transform(unsigned int state[4],unsigned char block[64]);
void MD5Encode(unsigned char *output,unsigned int *input,unsigned int len);
void MD5Decode(unsigned int *output,unsigned char *input,unsigned int len);
#endif

大神看看，这个宏定义有什么问题?

/data/data/com.n0n3m4.droidc/files/gcc/bin/../lib/gcc/arm-linux-androideabi/5.3.0/../../../../arm-linux-androideabi/lib/crtbegin_dynamic.o: In function `_start':
crtbrand.c:(.text+0x8c): undefined reference to `main'
collect2: error: ld returned 1 exit status

你应该把它和其他的代码一起编译，

而你只编译这些宏定义有卵用

这是md5源码:[无效] http://pan.baidu.com/s/1c2a4OfA
有兴趣的测试一下