c语言分段读取文本文件

#include "stdio.h"  

  

int main()  

{  

 FILE *pf=NULL   //文件指针  

  

 int filelen=0  

 int i=0  

 char *buf  

 pf=fopen("D:\\test.txt","r")   //以只读方式打开文件  

 if(pf==NULL)  

 {  

  return 0  

 }  

 else  

 {  

  //获得文件长度  

  

  fseek(pf,0,SEEK_END)   //文件指针移到末尾  

  filelen=ftell(pf)   //获得文件当前指针位置，即为文件长度  

  rewind(pf)   //将文清蔽件指针移到开头，准备读取  

  

  buf=malloc(filelen+1)    //新滑槐建缓冲区，存储独处的数据  

  //将缓冲区的数据设置为0  

  for(i=0i<filelen+1i++)  

   buf[i]=0  

  

  //读取文件  

  fread(buf,filelen,1,pf)  答让州

  //关闭文件  

  fclose(pf)  

  //buf中即为要读出的数据  

  

  printf("%s\n",buf)    //输出一下数据，你可以随便怎么用  

  free(buf)    //最后记得要释放  

 }  

 return 1  

}

进行数值凯滚分段主要进行字符串分割，使用strtok函数即可实现字符串分割。这里引用一段strtok用法：

The strtok() function returns a pointer to the next "token" in str1, where str2 contains the delimiters that determine the token. strtok() returns NULL if no token is found. In order to convert a string to tokens, the first call to strtok() should have str1 point to the string to be tokenized. All calls after this should have str1 be NULL.

For example:char str[] = "now # is the time for all # good men to come to the # aid of their country"

char delims[] = "#"

char *result = NULL

result = strtok( str, delims )

while( result != NULL ) {undefined

printf( "result is \"%s\"昌孙困\n", result )

result = strtok( NULL, delims )

}

/* 何问起 hovertree.com */

The above code will display the following output:

result is "now "耐念

result is " is the time for all "

result is " good men to come to the "

result is " aid of their country"

#include "stdio.h"

#include "math.h"

int main(int argc,char *argv[]){

double x,y

printf("Input x(R:)...\nx=")

scanf("%lf",&x)

if(x<5)

y=-x+3.5

else if(x>凳腔=5 && x<10)

y=20-3.5*pow(x+3,7)//这里看着像7,是几就把厅伍7改扮粗或成几

else

y=-3.5+sin(x)

printf("y = %g\t(x==%g)\n",y,x)

return 0

}

运行样例：

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