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  • c语言--查找某个区间的质数

    #include<stdio.h>
    #include<stdlib.h>
    
    struct int_e{
    	int *p;
    	int length;
    };
    
    int is_prime(int *primes,int length,int num){
     	int i;
    	for(i=0;i<length;i++){
      		if(*(primes+i)){
    			if(num%(*(primes+i))==0){
    				return 0;
    			}
    		}else{
    			//printf("%d--%d
    ",i,*(primes+i));
    			break;		}
    	}
    	return 1;
    }
    
    
    
    struct int_e primes(int limit){
    	
    	int max_num = limit/2;
    	int real_num = 1,i;
    	
    	int *primes = (int *)malloc(max_num*sizeof(int));
    	if(primes != NULL){
    		printf("茅坑太大了 没有");
    		//此处暂时不知道如何处理
    		return;
    	}
    	*primes = 2;
    	for(i=3;i<limit;i++){
    		if(is_prime(primes,max_num,i)){
    			*(primes+real_num)=i;
    			real_num++;
    		}
    	}
    	
    	primes = realloc(primes,real_num*sizeof(int));
    	struct int_e primes_info = {p:primes,length:real_num};
    	return primes_info;
    }
    
    
    
    void main(){
    	
    	struct int_e primes_info = primes(1000);
    	if(primes_info){
    		int length = primes_info.length,i;
    		int *primes = primes_info.p;
    	
    		printf("
    ========================
    ");
     		for(i=0;i<length;i++){
    			printf("%d -- %d
    ",i,*(primes+i));
    		}
    	}
    }
    
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  • 原文地址:https://www.cnblogs.com/liwuming/p/10469505.html
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