C代码对比，走心和不走心的程序猴

C估计是最普及的，几乎写代码都会抡两行出来，一听说写C写了240个月，那就得当面磕头，我还真见过时间越长代码越烂的（这个和英语4级是一样，大一过4级最容易，大四几乎很难过，因为从高中毕业就开始退化），所以我要说，好的代码和年纪没有关系，有些人就是好，有些人就是差，而且永远都不会长进。

对比下一个程序，从RSA的公钥里面取出公钥来，打印出来，这个其实就没啥功能，也能看出来水平高低？是的。

#include <string.h>

#include <openssl/err.h>
#include <openssl/pem.h>
#include <openssl/rsa.h>


static EVP_PKEY *__load_pubkey(BIO *err, const char *file, const char *key_descrip)
{
    BIO *key = NULL;
    EVP_PKEY *pkey = NULL;

    key = BIO_new(BIO_s_file());
if (key == NULL) {
        ERR_print_errors(err);
goto end;
    }
if (BIO_read_filename(key, file) <= 0) {
        BIO_printf(err, "Error opening %s %s\n", key_descrip, file);
        ERR_print_errors(err);
goto end;
    }

    pkey = PEM_read_bio_PUBKEY(key, NULL, NULL, NULL);

end:
if (key != NULL)
        BIO_free(key);
if (pkey == NULL)
        BIO_printf(err, "unable to load %s\n", file);
return (pkey);
}

int main(void)
{
    RSA *rsa = NULL;
    EVP_PKEY *pkey = NULL;
    BIO *bio_err = NULL;
    BIO *bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);

char *modulus_string, *exponent_string;
int i;

    bio_err = BIO_new_fp(stderr, BIO_NOCLOSE);

    pkey = __load_pubkey(bio_err, "./pub.key", "Public Key");
if (pkey == NULL)
return -1;

    rsa = EVP_PKEY_get1_RSA(pkey);
    EVP_PKEY_free(pkey);

    modulus_string = BN_bn2hex(rsa->n);
    exponent_string = BN_bn2hex(rsa->e);

    BIO_printf(bio_out, "#define CHNVIDEO_PUBLIC_MODULUS_ARRAY {");
for (i = 0; i < strlen(modulus_string); i++) {
        BIO_printf(bio_out, "0x%X,", modulus_string[i] + 0x80);
    }
    BIO_printf(bio_out, "}\n");

//BIO_printf(bio_out, "#define CHNVIDEO_PUBLIC_MODULUS \"%s\"\n", modulus_string);
    BIO_printf(bio_out, "#define CHNVIDEO_PUBLIC_EXPONENT \"%s\"\n", exponent_string);

if (bio_err)
        BIO_free(bio_err);
    BIO_free(bio_out);

return 0;
}

看另外一个：

#include <string.h>

#include <openssl/err.h>
#include <openssl/pem.h>
#include <openssl/rsa.h>

struct RsaCleaner
{
    BIO* out;
    BIO* err;
    BIO* key;
    EVP_PKEY* pkey;
    RSA* rsa;

    RsaCleaner() {
out = err = key = NULL;
        pkey = NULL;
    }

virtual ~RsaCleaner() {
if (out) {
            BIO_free(out);
        }
if (err) {
            BIO_free(err);
        }
if (key) {
            BIO_free(key);
        }
if (pkey) {
            EVP_PKEY_free(pkey);
        }
    }
};

int main(int argc, char** argv)
{
    RsaCleaner rc;

    rc.out = BIO_new_fp(stdout, BIO_NOCLOSE);
    rc.err = BIO_new_fp(stderr, BIO_NOCLOSE);

    rc.key = BIO_new(BIO_s_file());
if (!rc.key) {
        BIO_printf(rc.err, "Create pub key failed: ");
        ERR_print_errors(rc.err);
return -1;
    }

const char* file = "./objs/license/pub.key";
if (BIO_read_filename(rc.key, file) <= 0) {
        BIO_printf(rc.err, "Open pub key file %s failed: ", file);
        ERR_print_errors(rc.err);
return -1;
    }

    rc.pkey = PEM_read_bio_PUBKEY(rc.key, NULL, NULL, NULL);
if (!rc.pkey) {
        BIO_printf(rc.err, "Read pub key from %s failed.\n", file);
return -1;
    }

    rc.rsa = EVP_PKEY_get1_RSA(rc.pkey);
char* modulus = BN_bn2hex(rc.rsa->n);
char* exponent = BN_bn2hex(rc.rsa->e);

// output the header file.
    BIO_printf(rc.out, "// this file is auto generated\n"
"#ifndef AUTO_LICENSE_HPP\n#define AUTO_LICENSE_HPP\n\n");

    BIO_printf(rc.out, "#ifndef MODULUS\n #define MODULUS {");
for (char* p = modulus; *p; p++) {
if (((p - modulus) % 16) == 0) {
            BIO_printf(rc.out, "\\\n ");
        }
        BIO_printf(rc.out, "%#x, ", p[0]);
    }
    BIO_printf(rc.out, "\\\n }\n#endif\n");

    BIO_printf(rc.out, "#ifndef EXPONENT\n"
" #define EXPONENT \"%s\"\n#endif\n\n", exponent);

    BIO_printf(rc.out, "#endif\n\n");

return 0;
}

不要说后者是C++，所以比较优美，谁傻逼谁知道，C都写得烂的人写C++更烂，这就好残疾鸟，跑都跑不动，能飞起来么？