【C】标准库

算数函数

1. div_t div(int ,int);
2. ldiv_t ldiv(long int , long int );

int main(int args,char*argv[])
{
	div_t result;
	int a=23;
	int b=3;
	result = div(a,b);
	printf("result:%d %d",result.quot,result.rem);
	return 0;
}

随机数函数

3. int rand(void);
4. void srand(unsigned int ); 产生随机数种子，对随机数生成器初始化

int main(int args,char*argv[])
{
	srand((unsigned int)time(0));
	unsigned int i=0;
	unsigned temp= 0; 
	for(;i<10;i++)
	{
		temp = rand()%10;
		printf("%d\n",temp);
	}
}

字符转数值函数

5. int atoi(char const * string);
6. int strtoi(char const* string ,char** point ,int num);

数学函数

7. double sin(double);
8. double cos(double);
9. double tan(double);
10. double asin(double) ;
11. double acos(double);
12. double atan(double);
13. double sinh(double);
14. double cosh(double);
15. double tanh(double);
16. double exp(double);
17. double log(double);
18. double log10(double);
19. double frexp(double ,int *);
20. double ldexp(double, int *);
21. double modf(double,double *);

int main(int args,char* argv[])
{
	double temp;
	double re;
	re = modf(1.9999,&temp);//返回1.9999的小数部分，整数部分传回temp指针 
	printf("%f\n",re);
	printf("%f\n",temp);
	
	printf("%f\n",fmod(8.9999,2)) ; //返回8.9999 div 2 的余数 
	return 0;
}

22. double pow(double);
23. double sqrt(double);
24. double floor(double);返回不大于参数的最大整数
25. double ceil(double);返回不小于参数的最小整数
26. double fabs(double);返回参数的绝对值
27. double fmod(double,double);
28. double atof(char const *string);
29. double strtod(char const8 string,char ** unused);