随机字符串 [英] Random String
问题描述
任何人都可以建议如何创建一个生成
随机字符串的函数？
函数应该是：
int _RandomString（char ** str，int len）;
所以，它需要一个空字符串str并且它放入一个随机字符串
lenght len，否则返回1表示成功0否则。
提前致谢，
最好的问候，
Andrea
" Andrea" < ac ****** @ gmail.com写信息
新闻：11 ********************* @ k79g2000hse。 googlegro ups.com ...
任何人都可以建议如何创建一个生成
$的函数b $ b随机字符串？
函数应该是：
int _RandomString（char ** str，int len）;
所以，它需要一个空的字符串str并且它放入一个随机的字符串
lenght len，并且它返回1表示成功0否则。
在此先感谢，
最好的问候，
Andrea
希望这不是作业
（未经测试）
int randomstring（char ** str，int len）
{
char * answer = malloc（len + 1）;
int i;
if（answer）
{
for（i = 0; i< len; i ++）
answer [i] = randchar（）;
answer [len] = 0 ;
}
* str = answer;
回答？ 1：0;
}
/ *
这个由你决定。你是一个随意的角色是什么意思？
* /
char randchar（）
{
char answer ;
do
{
answer = rand（）％255;
}
while（！isalnum（ch））;
返回答案;
}
Andrea写道：
任何人都可以建议如何创建一个生成<的函数br />
随机字符串？
C库没有RNG，只提供了PRNG，即使是蒙特卡罗模拟，也可能不是
，远远少于任何安全
计划。
这是什么随机字符串用于？
从计算机获取随机数是一个非常难的问题，并且除非你有一些熵源，否则无法完成
类。您的操作系统
可能会提供这样的随机源，例如某些Intel CPU的
附带一个内置RNG。
函数应该是：
int _RandomString（char ** str，int len）;
所以，需要一个空字符串str，它放入一个随机字符串
lenght len，否则返回1表示成功0。
下划线前缀污染实施名称空间。
-
Tor< torust [at] online [dot] no>
Andrea说：
任何人都可以建议如何创建一个生成
随机字符串的函数？
函数应该是：
int _RandomString（char ** str，int len）;
你不能拥有前导下划线，因为_RandomString是保留的
供实现使用。但是你可以使用RandomString，如果你喜欢
。
所以，它需要一个空字符串str并且它放入一个随机字符串
lenght len，否则返回1表示成功0。
这是你可以做到的一种方式：
#include< stdlib.h>
#include< time.h>
#include< stdio.h>
int RandomString（char ** str，int len）
{
int rc = 0; / * 1表示成功* /
size_t len_ = len;
if（str！= NULL）
{
* str = malloc（len_ + 1）;
if（* str！= NULL）
{
const char sym [] =
" 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
" \"％^& *（）_- abcdefghijklmnopqrstuvwxyz"
" + = [] {} \\ |，<> /英寸;？ / *我错过了吗？ * /
size_t maxsym = sizeof sym / sizeof sym [0] - 1;
size_t i = 0;
while（i< len_）
{
int r = maxsym *（rand（）/（RAND_MAX + 1.0））;
（* str）[i ++ ] = sym [r];
}
（* str）[i] =''\ 0'';
rc = 1;
}
}
返回rc;
}
int main（无效）
{
int rc = 0;
int maxtrials = 20;
char * s = NULL;
srand（（无符号）时间（0））;
while（rc == 0&& maxtrials-- 0）
{
if（RandomString（& s，42））
{
printf（"％s \\ \\ n，s）;
免费;
}
}
返回0; < br $>
}
样本输出：
Gr ^ hlgopi> jcXhgr> Qv< + 0F /< L * tJ0WZsz3Y％rA5pu
i8WJ + TbhPXh * Wdr = R> [oXga" 0 / DA4] {m> M \ xh ^" \ = 3
XJgA6， 8 LT;Ĵ（bE\cD6mH< d {| + WR ^ KDV 8GuRx {Yr？TV * {
bX％o& A\ZowSae6？zJV |" BLK2k> 1？T（{{{SfT& _uDP9
o {FnqZ4k + G} 7Ib4JbYq％Ogv {.KXqYo + 8e1wP％=。O3 =
VLYZ（.yIX9zF0vZX_z8T | mVp / xd，7gw ^ [G] TCodbyX
qyFCIn> Q3 {？Zg / IE | Qvpuj \ j？4TcgD.R> B& Fy）[R（
N，&）8Wx] 8d-0I-4c6kp3 / nE％[？] U = G = BAQiJo％9w1j
wJD = wK）_N * G％| 5％xP？NAf5UO）& 6_8] sMqb）J4upL
IiQk" r。1Xcg ^ \ {.W> *（+ IscuKvy1（6JAW {cA + / CKb
sn ^ jk + gAR ^ T519Qx，RP0c" X％/ - O> l-_ZI> 4 [xl？A9S
GB ^），WzJXWkwyjR9g / jAY = 7 ^ q {9q1J4IU）pP {baN | F
5szW [" V] cuUjJ7aTxbd = t， U * JK2t_<< eou> cHT4tAY
YU），oP（MCLG_r" stFMoA = X {z.8E0 = PZLk \ GTImhV | x
] kJhYZ {9ar_" ; c& -q * W2 {imxz11} jW" ^ L7m]）8tgi（A
53eeu4.x< f * sZ）u | BDUeY％MO< U3b？am4eLiUQfDLGj
0gCvaN，{[TSBiN）mz（H）bwsFC5uQQ。< Rd788V2？KVR
V0f [mZT {\ {nl5 + q + C3x8VVG& * c）* w] wD] W2cxV ^ qMB
WS> 9EAC / I_TY / z> * PtU8 | J（< wORK0fWX | U）8 * k6nE"
7CM4idy / lsICn1" 1M％gjz-？Ri&> pDCBLOYQ |> A \ [B
第二个样本输出：
pxTxN< Y3Jr + ae，/ KYVd \o1F<％q）rdI& N1y6Pu（T？IF
axA_4-] h％eji-6T1x \KNGM8Nc [t} = / 7WvH} + rv ^ FU8
x] EC} /5BLMXTa.IO [5N。^ 4DT {} BT6（ ％{Vh2Mf8X = Uw
H {tZFh * ^ d，_rOYjZtp} HfMyiaZr，N7r * /（} D9WhmQA
Zfa40Pu \）VFR0psrk1yW）w [X.> udk6o6mKAna} f2Nv
UN）81C9 + -hjX0fUuE1 =] 7a9IIjAylXf1m8AnKJ-u = E
D = ti，a * xh0 \ zjb< 3ITjK1rUp> fKs％Y} OEZ | 8< X} dY
yYjUUmeoRyq4F％2umuH7m）L7ZU3yLgJ61 [％Vb16 [+ w
\ 1J< w\p ?? W] K * | fs = B / | C + V_XWeLJWEKgA2- + 2_Ja
to& TIHHTFB）2）0Z {fm9> = Ue / W8yZg3< UrYp.h | Qw4x
zcyL％Y，bWv \\ \\ .tO5eplhl2U6sRnli（q％QNLdql）N3OF
04 * 5iFrK + uf\_ | gFb7}？YFK>} \ * E.tT.xy2％？tm + -N
t3GUIs ^ 9r = O / zF {PU + 5ox] -zQ-f / UAM9D& * VH |（，uv
| g> x \ rk> 2 ^ + bOC6 {B" ; 0XbD [1A5， 20px | RvrJ9WHB + 4
nAHt0SG1rsFfuqlpslZcesSQ>％oEeaJNl" 2mtJn）/]
8sft ^ TZ]} 0hKRfn1uNc？bIZe} Fxfmw& ua4-？X<] P.（
bN7JP =）= + 36Mh /％" dAJ2 {u7Zt（UjwQASfId {56s \Az
EsxhEVrYYiE）3 | / Ycvqn9Q} nH> t。]] v4helw< ; XGT1U
= 50z& + gGaq_％ZpYE103％Tl20 ^> YjR0E）O0> BhDlTl
9tW- | 4y>）Dj-E7）erz1r0_21 * Djjz / Q，所以& mtNjL％N
-
Richard Heathfield
Usenet是一个奇怪的地方 - dmr 29/7/1999
http://www.cpax.org.uk
电子邮件：rjh在上述域名中， - www。
Hi,
Anyone could me suggest how to create a function that generates a
random string?
The function should be:
int _RandomString(char** str,int len);
so, it takes an empty string str and it puts in in a random string of
lenght len, and it returns 1 for success 0 otherwise.
Thanks in advance,
best regards,
Andrea
"Andrea" <ac******@gmail.comwrote in message
news:11*********************@k79g2000hse.googlegro ups.com...Hi,
Anyone could me suggest how to create a function that generates a
random string?
The function should be:
int _RandomString(char** str,int len);
so, it takes an empty string str and it puts in in a random string of
lenght len, and it returns 1 for success 0 otherwise.
Thanks in advance,
best regards,
Andrea
Hope this isn''t homework
(untested)
int randomstring(char **str, int len)
{
char *answer = malloc(len + 1);
int i;
if(answer)
{
for(i=0;i<len;i++)
answer[i] = randchar();
answer[len] = 0;
}
*str = answer;
return answer ? 1 : 0;
}
/*
This one is up to you. What do you mean by a random character?
*/
char randchar()
{
char answer;
do
{
answer = rand() % 255;
}
while(! isalnum(ch));
return answer;
}
Andrea wrote:Hi,
Anyone could me suggest how to create a function that generates a
random string?The C library has no RNG, only a PRNG is provided, which may not be
usable for even a Monte-Carlo simulations, far less for any security
programs.
What shall this "random" string be used for?
Getting random numbers from a computer, is a quite hard problem, and
cannot be done unless you have an entropy source of some kind. Your OS
might provide such a source for randomness, for example some Intel CPU''s
comes with a build-in RNG.
The function should be:
int _RandomString(char** str,int len);
so, it takes an empty string str and it puts in in a random string of
lenght len, and it returns 1 for success 0 otherwise.Underscore prefix is polluting the implementation name space.
--
Tor <torust [at] online [dot] no>
Andrea said:
Hi,
Anyone could me suggest how to create a function that generates a
random string?
The function should be:
int _RandomString(char** str,int len);You can''t have the leading underscore, since _RandomString is reserved
for use by the implementation. But you can have RandomString if you
like.
so, it takes an empty string str and it puts in in a random string of
lenght len, and it returns 1 for success 0 otherwise.Here''s one way you could do it:
#include <stdlib.h>
#include <time.h>
#include <stdio.h>
int RandomString(char **str, int len)
{
int rc = 0; /* 1 indicates success */
size_t len_ = len;
if(str != NULL)
{
*str = malloc(len_ + 1);
if(*str != NULL)
{
const char sym[] =
"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"\"%^&*()_-abcdefghijklmnopqrstuvwxyz"
"+=[]{}\\|,<.>/?"; /* did I miss any? */
size_t maxsym = sizeof sym / sizeof sym[0] - 1;
size_t i = 0;
while(i < len_)
{
int r = maxsym * (rand() / (RAND_MAX + 1.0));
(*str)[i++] = sym[r];
}
(*str)[i] = ''\0'';
rc = 1;
}
}
return rc;
}
int main(void)
{
int rc = 0;
int maxtrials = 20;
char *s = NULL;
srand((unsigned)time(0));
while(rc == 0 && maxtrials-- 0)
{
if(RandomString(&s, 42))
{
printf("%s\n", s);
free(s);
}
}
return 0;
}
Sample output:
Gr^hlgopi>jcXhgr>Qv<+0F/<L*tJ0WZsz3Y%rA5pu
i8WJ+TbhPXh*Wdr=R>[oXga"0/DA4]{m>M\xh^"\=3
XJgA6,8<j(bE\cD6mH<d{|+wr^KDV8GuRx{Yr?TV*{
bX%o&A\ZowSae6?zJV|"BLK2k>1?T({{{SfT&_uDP9
o{FnqZ4k+G}7Ib4JbYq%Ogv{.KXqYo+8e1wP%=.O3=
VLYZ(.yIX9zF0vZX_z8T|mVp/xd,7gw^[G]TCodbyX
qyFCIn>Q3{?Zg/IE|Qvpuj\j?4TcgD.R>B&Fy")[R(
N,&)8Wx]8d-0I-4c6kp3/nE%[?]U=G=BAQiJo%9w1j
wJD=wK)_N*G%|5%x"P?N"Af5UO)&6_8]sMqb)J4upL
IiQk"r."1Xcg^\{.W>*(+IscuKvy1(6JAW{cA+/CKb
sn^jk+gAR^T519Qx,RP0c"X%/-O>l-_ZI>4[xl?A9S
GB^),WzJXWkwyjR9g/jAY=7^q{9q1J4IU)pP{baN|F
5szW["V)cuUjJ7aTxbd=t,U*JK2t_<<eou>cHT4tAY
YU),oP(MCLG_r"stFMoA=X{z.8E0=PZLk\GTImhV|x
]kJhYZ{9ar_"c&-q*W2{imxz11)jW"^L7m])8tgi(A
53eeu4.x<f*sZ)u|BDUeY%MO<U3b?am4eLiUQfDLGj
0gCvaN,{[TSBiN)mz(H)bwsFC5uQQ.<Rd788V2?KVR
V0f[mZT{\{nl5+q+C3x8VVG&*c)*w]wD]W2cxV^qMB
WS>9EAC/I_TY/z>*PtU8|J(<wORK0fWX|U)8*k6nE"
7CM4idy/lsICn1"1M%gjz-?Ri&>pDCBLOYQ|>A\i[B
Second sample output:
pxTxN<Y3Jr+ae,/KYVd\o1F<%q)rdI&N1y6Pu(T?IF
axA_4-]h%eji-6T1x\KNGM8Nc[t}=/7WvH}+rv^FU8
x]EC}/5BLMXTa.IO[5N.^4DT{}BT6(%{Vh2Mf8X=Uw
H{tZFh*^d,_rOYjZtp}HfMyiaZr,N7r*/(}D9WhmQA
Zfa40Pu\)VFR0psrk1yW)w[X.>udk6o6mKAna}f2Nv
UN)81C9+-hjX0fUuE1=]7a9IIjAylXf1m8AnKJ-u=E
D=t-i,a*xh0\zJb<3ITjK1rUp>fKs%Y}OEZ|8<X}dY
yYjUUmeoRyq4F%2umuH7m)L7ZU3yLgJ61[%Vb16[+w
\1J<w\p??W)K*|f-s=B/|C+V_XWeLJWEKgA2-+2_Ja
to&TIHHTFB)2)0Z{fm9>=Ue/W8yZg3<UrYp.h|Qw4x
zcyL%Y,bWv\.tO5eplhl2U6sRnli(q%QNLdql)N3OF
04*5iFrK+uf\_|gFb7}?YFK>}\*E.tT.xy2%?tm+-N
t3GUIs^9r=O/zF{PU+5ox]-zQ-f/UAM9D&*VH|(,uv
|g>x\Rk>2^+bOC6{B"0XbD[1a5,20px|RvrJ9WHB+4
nAHt0SG1rsFfuqlpslZcesSQ>%oEeaJNl"2mtJn)/]
8sft^TZ]}0hKRfn1uNc?bIZe}Fxfmw&ua4-?X<]P.(
bN7JP=)=+36Mh/%"dAJ2{u7Zt(UjwQASfId{56s\Az
EsxhEVrYYiE)3|/Ycvqn9Q}nH>t.]]v4helw<XGT1U
=5Oz&+gGaq_%ZpYElO3%Tl20^>YjR"0E)O0>BhDlTl
9tW-|4y>)Dj-E7)erz1r0_21*Djjz/Q,so&mtNjL%N
--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at the above domain, - www.
这篇关于随机字符串的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
