#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
int main () {
//字符串换数字
printf("%d\n",atoi("123"));
printf("%g\n",atof("67.9"));
//数字换字符串
//可以把10进制修改为别的进制
int number=175;
char *c;
sprintf(c,"%x",number);
puts(c);
//字符串换数字
//把别的进制换成10进制
char c1[10]={"11)(11a"}; char* c2;
int ans=strtol(c1,&c2,10);
printf("\nans=%d and c2=%s",ans,c2);
char str[50];
strcpy(str,"This is string.h library function");
puts(str);
memset(str,'$',strlen(str));
puts(str);
int a[10];
memset(a,0,sizeof(a));
for(int i=0;i<10;i++)
printf("%d ",a[i]);
}