# gmp_nextprime

(PHP 5 >= 5.2.0, PHP 7, PHP 8)

gmp_nextprimeFind next prime number

### 说明

gmp_nextprime( `\$num`): GMP

Find next prime number

### 参数

`num`

GMP 对象或 int ，或数字string

### 返回值

Return the next prime number greater than `num`, as a GMP number.

### 示例

`<?php\$prime1 = gmp_nextprime(10); // next prime number greater than 10\$prime2 = gmp_nextprime(-1000); // next prime number greater than -1000echo gmp_strval(\$prime1) . "\n";echo gmp_strval(\$prime2) . "\n";?>`

```11
2```

### 注释

This function uses a probabilistic algorithm to identify primes and chances to get a composite number are extremely small.

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### User Contributed Notes 3 notes

Tommy Lynge Jrgensen
7 years ago
`Prime numbers are positive, non-zero numbers that have exactly two factors. No more, no less. So testing negative numbers doesn't really make any sense.`
IceMetalPunk at gmail dot com
7 years ago
`Negative numbers N always have at least four factors: N*1=N and abs(N)*-1=N. Therefore, even if "natural number" weren't in the definition of a prime (which it is), no negative number would ever qualify. Therefore, the next-largest prime number to any negative number is always 2.`
-1
Anonymous
8 years ago
`It seems gmp_nextprime on negative numbers always returns 2.`