C語言srand(time(0))

這是用于初始化隨機函數發(fā)生器的，計算機中的隨機函數在生成一個隨機數時需要用到一個稱為隨機數發(fā)生器的東西，如果不對其進行初始化，每次生成的隨機數就會是相同的。

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srand函數就用來初始化這個發(fā)生器，參數time(0)能夠生成從1970年1月1日到當前機器時間的秒數，這個數在你每次執(zhí)行程序的時候都會不斷增長、變化，所以用它當做種子來初始化發(fā)生器，就會生成不同的隨機數了。

求一個正確的基于51單片機的函數信號發(fā)生器的C程序

#includereg51.h

#includeabsacc.h

#includeMAX72191.h

#defineDAC XBYTE[0x7fff] //P2.7接CS

sbitkey0 = P3^2;// 增減切換鍵

sbitkey1 = P3^3;//個位,十位，百位，千位的控制切換

sbitkey2 = P3^4;// 調整位

sbitkey3 = P3^5;// 波形選擇正弦、三角、矩形波，鋸齒波

unsignedchar i,j;

unsignedint counter,step,flag;

typedefunsigned int uint;

//定時器0初始化

voidInit_Timer0(void)

{

TMOD = (TMOD 0XF0) | 0X01;//設置工作方式和定時初始值

TH0 = 0xff;

TL0 = 0x00;

TR0 =1; //啟動定時器

ET0 =1;

}

//定義輸出波形的代碼

unsignedchar code type[4][256]={

{ //正弦波代碼

0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x1, 0x1, 0x2, 0x3, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8,

0x9, 0xb,0xc, 0xd, 0xf, 0x10,0x12,0x13,0x15,0x17,0x19,0x1b,0x1d,0x1f,0x21,0x23,

0x25,0x27,0x2a,0x2c,0x2e,0x31,0x33,0x36,0x39,0x3b,0x3e,0x41,0x43,0x46,0x49,0x4c,

0x4f,0x52,0x55,0x58,0x5b,0x5e,0x61,0x64,0x67,0x6a,0x6d,0x70,0x73,0x76,0x7a,0x7d,

0x80,0x83,0x86,0x89,0x8c,0x8f,0x93,0x96,0x99,0x9c,0x9f,0xa2,0xa5,0xa8,0xab,0xae,

0xb1,0xb4,0xb6,0xb9,0xbc,0xbf,0xc1,0xc4,0xc7,0xc9,0xcc,0xce,0xd1,0xd3,0xd5,0xd8,

0xda,0xdc,0xde,0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xeb,0xed,0xef,0xf0,0xf1,0xf3,0xf4,

0xf5,0xf6,0xf8,0xf9,0xf9,0xfa,0xfb,0xfc,0xfc,0xfd,0xfd,0xfe,0xfe,0xfe,0xfe,0xfe,

0xfe,0xfe,0xfe,0xfe,0xfe,0xfd,0xfd,0xfc,0xfc,0xfb,0xfa,0xf9,0xf9,0xf8,0xf6,0xf5,

0xf4,0xf3,0xf1,0xf0,0xef,0xed,0xeb,0xea,0xe8,0xe6,0xe4,0xe2,0xe0,0xde,0xdc,0xda,

0xd8,0xd5,0xd3,0xd1,0xce,0xcc,0xc9,0xc7,0xc4,0xc1,0xbf,0xbc,0xb9,0xb6,0xb4,0xb1,

0xae,0xab,0xa8,0xa5,0xa2,0x9f,0x9c,0x99,0x96,0x93,0x8f,0x8c,0x89,0x86,0x83,0x80,

0x7d,0x7a,0x76,0x73,0x70,0x6d,0x6a,0x67,0x64,0x61,0x5e,0x5b,0x58,0x55,0x52,0x4f,

0x4c,0x49,0x46,0x43,0x41,0x3e,0x3b,0x39,0x36,0x33,0x31,0x2e,0x2c,0x2a,0x27,0x25,

0x23,0x21,0x1f,0x1d,0x1b,0x19,0x17,0x15,0x13,0x12,0x10,0xf,0xd, 0xc, 0xb, 0x9,

0x8,0x7, 0x6, 0x5, 0x4, 0x3, 0x3, 0x2, 0x1, 0x1, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00

},

{ //三角波代碼

0x2,0x4, 0x6, 0x8, 0xa, 0xc, 0xe, 0x10,0x12,0x14, 0x16, 0x18, 0x1a,0x1c, 0x1e, 0x20,

0x22,0x24, 0x26, 0x28, 0x2a, 0x2c, 0x2e, 0x30,0x32, 0x34, 0x36, 0x38, 0x3a, 0x3c, 0x3e, 0x40,

0x42,0x44, 0x46, 0x48, 0x4a, 0x4c, 0x4e, 0x50,0x52, 0x54, 0x56, 0x58, 0x5a, 0x5c, 0x5e, 0x60,

0x62,0x64, 0x66, 0x68, 0x6a, 0x6c, 0x6e, 0x70,0x72, 0x74, 0x76, 0x78, 0x7a, 0x7c, 0x7e, 0x80,

0x82,0x84, 0x86, 0x88, 0x8a, 0x8c, 0x8e, 0x90,0x92, 0x94, 0x96, 0x98, 0x9a, 0x9c, 0x9e, 0xa0,

0xa2,0xa4, 0xa6, 0xa8, 0xaa, 0xac, 0xae, 0xb0,0xb2, 0xb4, 0xb6, 0xb8, 0xba, 0xbc,0xbe, 0xc0,

0xc2,0xc4, 0xc6, 0xc8, 0xca, 0xcc, 0xce, 0xd0,0xd2, 0xd4, 0xd6, 0xd8, 0xda, 0xdc,0xde, 0xe0,

0xe2,0xe4, 0xe6, 0xe8, 0xea, 0xec, 0xee, 0xf0,0xf2, 0xf4, 0xf6, 0xf8, 0xfa, 0xfc,0xfe, 0xff,

0xfe,0xfc, 0xfa, 0xf8, 0xf6, 0xf4, 0xf2, 0xf0,0xee, 0xec, 0xea, 0xe8, 0xe6, 0xe4,0xe2, 0xe0,

0xde,0xdc, 0xda, 0xd8, 0xd6, 0xd4, 0xd2, 0xd0,0xce, 0xcc, 0xca, 0xc8, 0xc6, 0xc4,0xc2, 0xc0,

0xbe,0xbc, 0xba, 0xb8, 0xb6, 0xb4, 0xb2, 0xb0,0xae, 0xac, 0xaa, 0xa8, 0xa6, 0xa4,0xa2, 0xa0,

0x9e, 0x9c, 0x9a, 0x98, 0x96, 0x94, 0x92, 0x90,0x8e, 0x8c, 0x8a, 0x88, 0x86, 0x84, 0x82, 0x80,

0x7e, 0x7c, 0x7a, 0x78, 0x76, 0x74, 0x72, 0x70,0x6e, 0x6c, 0x6a, 0x68, 0x66, 0x64, 0x62, 0x60,

0x5e, 0x5c, 0x5a, 0x58, 0x56, 0x54, 0x52, 0x50,0x4e, 0x4c, 0x4a, 0x48, 0x46, 0x44, 0x42, 0x40,

0x3e, 0x3c, 0x3a, 0x38, 0x36, 0x34, 0x32, 0x30,0x2e, 0x2c, 0x2a, 0x28, 0x26, 0x24, 0x22, 0x20,

0x1e, 0x1c, 0x1a, 0x18, 0x16, 0x14, 0x12, 0x10,0xe, 0xc, 0xa, 0x8, 0x6, 0x4, 0x2, 0x00

},

{// 矩形脈沖波代碼

0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,

0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,

0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,

0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,

0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,

0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,

0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,

0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff, 0xff, 0xff, 0xff, 0xff,0xff, 0xff,

0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,

0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,

0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,

0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,

0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,

0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,

0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,

0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00, 0x00, 0x00, 0x00, 0x00,0x00, 0x00,

},

{//鋸齒波代碼

0x00,0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,0x08,0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,

0x10,0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,0x18,0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,

0x20,0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,0x28,0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,

0x30,0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,0x38,0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,

0x40,0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,0x48,0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,

0x50,0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,0x58,0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,

0x60,0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,0x68,0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,

0x70,0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,0x78,0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,

0x80,0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,0x88,0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,

0x90,0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,0x98,0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,

0xa0,0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,0xa8,0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,

0xb0,0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,0xb8,0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,

0xc0,0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,0xc8,0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,

0xd0,0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,0xd8,0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,

0xe0,0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,0xe8,0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,

0xf0,0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,0xf8,0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff}

};

//顯示子函數

Disp7219(unsignedlong dat)

{

unsigned char i;

unsigned char led[8];

led[7]=dat%10;

led[6]=dat/10%10;

led[5]=dat/100%10;

led[4]=dat/1000%10;

led[3]=dat/10000%10;

led[2]=dat/100000%10;

led[1]=dat/1000000%10;

led[0]=dat/10000000%10;

for(i=0;i8;i++)

{

max_7219(i+1, led[i]);

}

}

//延時約1m秒

voiddelay_ms(uint n)

{

uchar j;

while(n--)

for(j=0;j120;j++);

}

//主函數

main()

{

unsigned int f,n,j;

delay_ms(500);

Init_Max7219();//初始化7219

Disp7219(000);

Init_Timer0();

step=18;

EA = 1;

while(1)

{

if(key0 == 0) n=n+1;

if(n==2)n=0;

if(key1==0) j=j+1;

if(j==4) j=0;

if(n==0 j == 0 key2 == 0) if(step180) step+=18; //個位增

if(n==1 j == 0 key2 == 0) if(step18) step-=18; //個位減

if(n==0 j == 1 key2 == 0) if(step1800) step+=180;//十位增

if(n==1 j == 1 key2 == 0) if(step180) step-=180; //十位減

if(n==0 j == 2 key2 == 0) if(step18000) step+=1800;//百位增

if(n==1 j == 2 key2 == 0) if(step1800) step-=1800;//百位減

if(n==0 j == 3 key2 == 0) if(step54000) step+=18000;//千位增

if(n==1 j == 3 key2 == 0) if(step18000) step-=18000;//千位減

if(key3==0)flag=flag+1;if(flag==4)flag=0;

while((!key0)||(!key1)||(!key2)||(!key3));

f=step/18;

Disp7219(f);}//顯示頻率

}

// 定時中斷服務

voidTimer0(void) interrupt 1 using 2

{

TH0 = 0xff;

TL0 = 0x00;

counter = counter + step;

DAC=type[flag][(unsignedint)counter8];

}

跪求單片機大神幫我解析下面函數信號發(fā)生器的代碼（C語言）

你貼的代碼里那幾個數組沒有用到啊，暫時不知道干什么的，初步猜測估計是液晶的點陣數據，main函數里也就是初始化了定時器和lcd液晶屏，不停的掃描按鍵鍵值，定時中斷里應該還有很多東西，這里看不到。

需要問具體的話可以把程序發(fā)我郵箱吧：cxz1088cxz@vip.qq.com

簡易函數信號發(fā)生器C語言編寫

我沒做過正弦波和三角波，我認為正弦波做的話用帶DA功能的單片機，但是你沒說正弦波的頻率和賦值，三角波也可以用DA做，方波就很簡單了用拉高活拉低口線就可以了。你直接用單片機做，不用外圍電路嗎？？