c语言中u8,u16,u32和int区别
这几种方式都是在表达同1个意思，没有区别。
typedef unsigned char uint8_t;
typedef unsigned short int uint16_t;
typedef unsigned int uint32_t;
typedef unsigned __int64 uint64_t;
代码示例：
voidTIM3_Int_Init(u16arr,u16psc)
{
//dosomething…
}
扩展资料
u8,u16,u32的使用
示例：
#defineU32 unsignedint
#defineU16 unsignedshort
#defineS32 int
#defineS16 shortint
#defineU8 unsignedchar
#defineS8 char
unsignedchar=u8
unsignedshortint=u16
unsignedlongint=u32
C语言 获取网卡最大速度
#include string.h
#include sys/ioctl.h
#include string.h
#include errno.h
#include linux/sockios.h
#include net/if.h
#include stdio.h
#include stdint.h
#include stddef.h
#include stdlib.h
#include sys/stat.h
#include sys/types.h
#include sys/socket.h
#ifndef SIOCETHTOOL
#define SIOCETHTOOL 0x8946
#endif
#ifndef ARRAY_SIZE
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
#endif
/* CMDs currently supported */
#define ETHTOOL_GSET 0x00000001 /* Get settings. */
#define ETHTOOL_SSET 0x00000002 /* Set settings. */
/* hack, so we may include kernel’s ethtool.h */
//typedef unsigned long long __u64;
typedef __uint32_t __u32; /* ditto */
typedef __uint16_t __u16; /* ditto */
typedef __uint8_t __u8; /* ditto */
/* The forced speed, 10Mb, 100Mb, gigabit, 2.5Gb, 10GbE. */
#define SPEED_10 10
#define SPEED_100 100
#define SPEED_1000 1000
#define SPEED_2500 2500
#define SPEED_10000 10000
/* This should work for both 32 and 64 bit userland. */
struct ethtool_cmd {
__u32 cmd;
__u32 supported; /* Features this interface supports */
__u32 advertising; /* Features this interface advertises */
__u16 speed; /* The forced speed, 10Mb, 100Mb, gigabit */
__u8 duplex; /* Duplex, half or full */
__u8 port; /* Which connector port */
__u8 phy_address;
__u8 transceiver; /* Which transceiver to use */
__u8 autoneg; /* Enable or disable autonegotiation */
__u32 maxtxpkt; /* Tx pkts before generating tx int */
__u32 maxrxpkt; /* Rx pkts before generating rx int */
__u32 reserved[4];
};
int main(int argc, char *argp[])
{
if(argc != 2)
{
fprintf(stdout, “parameter is erro . usage : getNet ethXX!\n”);
return 1;
}
char *devname;
devname = argp[1] ; // 取得网卡名
//devname = “eth0” ; // 取得网卡名
/*
ifreq结构定义在/usr/include\net/if.h，用来配置ip地址，激活接口，配置MTU等接口信息的。
其中包含了一个接口的名字和具体内容——（是个共用体，有可能是IP地址，广播地址，子网掩码，MAC号，MTU或其他内容）。
ifreq包含在ifconf结构中。而ifconf结构通常是用来保存所有接口的信息的。
*/
struct ifreq ifr, *ifrp; // 接口请求结构
int fd; // to access socket 通过socket访问网卡的 文件描述符号fd
/* Setup our control structures. */
memset(ifr, 0, sizeof(ifr));
strcpy(ifr.ifr_name, devname);
/* Open control socket. */
fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd 0) {
perror(“Cannot get control socket”);
return 70;
}
int err;
struct ethtool_cmd ep;
//fprintf(stdout, “Settings for %s:\n”, devname);
ep.cmd = ETHTOOL_GSET; // ethtool-copy.h:380:#define ETHTOOL_GSET 0x00000001 /* Get settings. */
ifr.ifr_data = (caddr_t)ep; // caddr_t 是void类型，而这句话是什么意思
err = ioctl(fd, SIOCETHTOOL, ifr); // int ioctl(int handle, int cmd,[int *argdx, int argcx]);
if (err != 0) { // 如果出错退出;
printf(” ioctl is erro .\n”);
return -1;
}
// =========== 输出 网卡速度；============
fprintf(stdout, “%s Speed: “, devname );
switch (ep.speed) {
case SPEED_10:
fprintf(stdout, “10Mb/s\n”);
break;
case SPEED_100:
fprintf(stdout, “100Mb/s\n”);
break;
case SPEED_1000:
fprintf(stdout, “1000Mb/s\n”);
break;
case SPEED_2500:
fprintf(stdout, “2500Mb/s\n”);
break;
case SPEED_10000:
fprintf(stdout, “10000Mb/s\n”);
break;
default:
fprintf(stdout, “Unknown! (%i)\n”, ep.speed);
break;
};
return 0;
}
在c语言中，使用全局变量找出数组中最大和最小数
#includestdio.h
int max,min;
void findmaxmin(int a[],int n)
{int i;
max=min=a[0];
for(i=1;in;i++)
if(maxa[i])max=a[i];
else if(mina[i])min=a[i];
}
int main()
{int a[10]={5,6,9,0,1,2,3,8,45,12};
findmaxmin(a,10);
printf(“max=%d\nmin=%d\n”,max,min);
return 0;
}
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