[英]Generating random string unsigned char in C
I want to generate a random string text of length 100 with the code below, then to verify that I print the length of the variable text but sometimes that is less than 100. How can I fix that? 我想用下面的代码生成长度为100的随机字符串文本,然后验证我是否打印了变量文本的长度,但有时小于100.如何解决这个问题?
#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>
int main() {
int i, LEN = 100;
srandom(time(NULL));
unsigned char text[LEN];
memset(text, 1, LEN);
for (i = 0; i < LEN; i++) {
text[i] = (unsigned char) rand() & 0xfff;
}
printf("plain-text:");
printf("strlen(text)=%zd\n", strlen(text));
}
Perhaps a random character 0
was added to the string, and then it is considered as the end of string by strlen
. 也许随机字符
0
被添加到字符串中,然后它被strlen
视为字符串的结尾。
You can generate random characters as (rand() % 255) + 1
to avoid zeros. 您可以生成随机字符
(rand() % 255) + 1
以避免零。
And at the end you have to zero-terminate the string. 最后你必须对字符串进行零终止。
LEN = 101; // 100 + 1
....
for (i = 0; i < LEN - 1; i++) {
text[i] = (unsigned char) (rand() % 255 + 1);
}
text[LEN-1] = 0;
I want to generate a random string text of length 100 with the code below, then to verify that I print the length of the variable text but sometimes that is less than 100. How can I fix that?
我想用下面的代码生成长度为100的随机字符串文本,然后验证我是否打印了变量文本的长度,但有时小于100.如何解决这个问题?
First of all, if you want to generate a string of length 100, you'll need to declare an array of size 101. 首先,如果要生成长度为100的字符串,则需要声明一个大小为101的数组。
int i, LEN = 101; srandom(time(NULL)); unsigned char text[LEN];
When you are assigning the characters from the call to rand
, make sure that it is not 0
, which is usually the null terminator for strings. 当您将调用中的字符分配给
rand
,请确保它不是0
,这通常是字符串的空终止符。
for (i = 0; i < LEN - 1; /* Don't increment i here */) { c = (unsigned char) rand() & 0xfff; if ( c != '\\0' ) { text[i] = c; // Increment i only for this case. ++i } }
and don't forget to null terminate the string. 并且不要忘记null终止字符串。
text[LEN-1] = '\\0';
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