关于memset

int

注：”较“的原则：加法不爆。

• 极大值：0x7f
• 较大值：0x3f
• 较小值：0xc0
• 极小值：0x80

long long

注：”较“的原则：加法不爆。

• 极大值：0x7f
• 较大值：0x3f
• 较小值：0xc0
• 极小值：0x80

double

注：”较“的原则：保证一定位精度。

• 极大值：0x7f
• 较大值：0x43
• 较小值：0xc2
• 极小值：0xfe

float （这个有用吗）

注：”较“的原则：保证一定位精度。

• 极大值：0x7f
• 较大值：0x4f
• 较小值：0xce
• 极小值：0xfe

```cpp
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#define N 5
using namespace std;
int a[N];
long long b[N];
float c[N];
double d[N];
void _int()
{
puts("");
puts("int:");</algorithm></iostream></cstring></cstdio>

puts("");
memset(a,0x7f,sizeof a);printf("%d\n",a[0]);
memset(a,0x80,sizeof a);printf("%d\n",a[0]);
memset(a,0x81,sizeof a);printf("%d\n",a[0]);

puts("");
memset(a,0xbf,sizeof a);printf("%d %d\n",a[0],a[0]*2);
memset(a,0xc0,sizeof a);printf("%d %d\n",a[0],a[0]*2);
memset(a,0xc1,sizeof a);printf("%d %d\n",a[0],a[0]*2);

puts("");
memset(a,0x3e,sizeof a);printf("%d %d\n",a[0],a[0]*2);
memset(a,0x3f,sizeof a);printf("%d %d\n",a[0],a[0]*2);
memset(a,0x40,sizeof a);printf("%d %d\n",a[0],a[0]*2);

puts("");
memset(a,0x7e,sizeof a);printf("%d\n",a[0]);
memset(a,0x7f,sizeof a);printf("%d\n",a[0]);
memset(a,0x80,sizeof a);printf("%d\n",a[0]);

}
void _long()
{
puts("");
puts("long long:");

puts("");
memset(b,0x7f,sizeof b);printf("%I64d\n",b[0]);
memset(b,0x80,sizeof b);printf("%I64d\n",b[0]);
memset(b,0x81,sizeof b);printf("%I64d\n",b[0]);

puts("");
memset(b,0xbf,sizeof b);printf("%I64d %I64d\n",b[0],b[0]*2);
memset(b,0xc0,sizeof b);printf("%I64d %I64d\n",b[0],b[0]*2);
memset(b,0xc1,sizeof b);printf("%I64d %I64d\n",b[0],b[0]*2);

puts("");
memset(b,0x3e,sizeof b);printf("%I64d %I64d\n",b[0],b[0]*2);
memset(b,0x3f,sizeof b);printf("%I64d %I64d\n",b[0],b[0]*2);
memset(b,0x40,sizeof b);printf("%I64d %I64d\n",b[0],b[0]*2);

puts("");
memset(b,0x7e,sizeof b);printf("%I64d\n",b[0]);
memset(b,0x7f,sizeof b);printf("%I64d\n",b[0]);
memset(b,0x80,sizeof b);printf("%I64d\n",b[0]);

}
void _float()
{
puts("");
puts("float:");

puts("");
memset(c,0xfd,sizeof c);printf("%f\n",c[0]);
memset(c,0xfe,sizeof c);printf("%f\n",c[0]);
memset(c,0xff,sizeof c);printf("%f\n",c[0]);

puts("");
memset(c,0xcd,sizeof c);printf("%f %f\n",c[0],c[0]*2);
memset(c,0xce,sizeof c);printf("%f %f\n",c[0],c[0]*2);
memset(c,0xcf,sizeof c);printf("%f %f\n",c[0],c[0]*2);

puts("");
memset(c,0x4e,sizeof c);printf("%f %f\n",c[0],c[0]*2);
memset(c,0x4f,sizeof c);printf("%f %f\n",c[0],c[0]*2);
memset(c,0x50,sizeof c);printf("%f %f\n",c[0],c[0]*2);

puts("");
memset(c,0x7e,sizeof c);printf("%.15f\n",c[0]);
memset(c,0x7f,sizeof c);printf("%.15f\n",c[0]);
memset(c,0x80,sizeof c);printf("%.15f\n",c[0]);

}
void _double()
{
puts("");
puts("double:");

puts("");
memset(d,0xfd,sizeof d);printf("%lf\n",d[0]);
memset(d,0xfe,sizeof d);printf("%lf\n",d[0]);
memset(d,0xff,sizeof d);printf("%lf\n",d[0]);

puts("");
memset(d,0xc1,sizeof d);printf("%lf %lf\n",d[0],d[0]*2);
memset(d,0xc2,sizeof d);printf("%lf %lf\n",d[0],d[0]*2);
memset(d,0xc3,sizeof d);printf("%lf %lf\n",d[0],d[0]*2);

puts("");
memset(d,0x42,sizeof d);printf("%lf %lf\n",d[0],d[0]*2);
memset(d,0x43,sizeof d);printf("%lf %lf\n",d[0],d[0]*2);
memset(d,0x44,sizeof d);printf("%lf %lf\n",d[0],d[0]*2);

puts("");
memset(d,0x7e,sizeof d);printf("%lf\n",d[0]);
memset(d,0x7f,sizeof d);printf("%lf\n",d[0]);
memset(d,0x80,sizeof d);printf("%lf\n",d[0]);

}
int main()
{
_int();
_long();
_float();
_double();
}