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[C] Generate Random String From [a-z0-9]
source link: http://siongui.github.io/2017/02/09/c-generate-random-string/
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[C] Generate Random String From [a-z0-9]
February 09, 2017
Generate a random string from [a-z0-9] in C programming language.
ranstr.c | repository | view raw
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* alphabet: [a-z0-9] */
const char alphabet[] = "abcdefghijklmnopqrstuvwxyz0123456789";
/**
* not a cryptographically secure number
* return interger [0, n).
*/
int intN(int n) { return rand() % n; }
/**
* Input: length of the random string [a-z0-9] to be generated
*/
char *randomString(int len) {
char *rstr = malloc((len + 1) * sizeof(char));
int i;
for (i = 0; i < len; i++) {
rstr[i] = alphabet[intN(strlen(alphabet))];
}
rstr[len] = '\0';
return rstr;
}
int main(int argc, char **argv) {
// the seed for a new sequence of pseudo-random integers
// to be returned by rand()
srand(time(NULL));
char *p;
p = randomString(10);
printf("%s\n", p);
free(p);
p = randomString(11);
printf("%s\n", p);
free(p);
p = randomString(12);
printf("%s\n", p);
free(p);
}
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