一个程序在VC运行不了！高手帮改下！谢拉！

--------------------Configuration: PROG - Win32 Debug--------------------
Linking...
PROG.OBJ : error LNK2001: unresolved external symbol _isprime
Debug/PROG.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

PROG.exe - 2 error(s), 0 warning(s)
-----------------------------------------------------------------------------------------------------
#include<stdio.h>
int a[300],b[300],cnt=0;
void readDat();
void writeDat();

int isP(int m)
{
int i;
for(i=2;i<m;i++)
     if(m%i==0) return 0;
return 1;
}

void jsValue()
{
    int i,j;
    int temp;
    for(i=0;i<300;i++)
        if(isprime(a[i]))
        {
            b[cnt]=a[i];
            cnt++;
        }
        for(i=0;i<cnt-1;i++)
            for(j=i+1;j<cnt;j++)
                if(b[i]>b[j])
                {
                    temp=b[i];
                    b[i]=b[j];
                    b[j]=temp;
                }
}

void main()
{
int i;
readDat();
jsValue();
writeDat();
printf("cnt=%d\n",cnt);
for(i=0;i<cnt;i++)
     printf("b[%d]=%d\n",i,b[i]);
}

void readDat()
{
FILE *fp;
int i;
fp=fopen("IN39.DAT","r");
for(i=0;i<300;i++)
     fscanf(fp,"%d,",&a[i]);
fclose(fp);
}

void writeDat()
{
FILE *fp;
int i;
fp=fopen("OUT39.DAT","w");
fprintf(fp,"%d\n",cnt);
for(i=0;i<cnt;i++)
    fprintf(fp, "%d\n",b[i]);
fclose(fp);
}
----------------解决方案--------------------------------------------------------
#include<stdio.h>
int a[300],b[300],cnt=0;
void readDat();
void writeDat();

int isP(int m)
{
int i;
for(i=2;i<m;i++)
     if(m%i==0) return 0;
return 1;
}

void jsValue()
{
    int i,j;
    int temp;
    for(i=0;i<300;i++)
        if(isprime(a[i]))        {    这里有错吧
            b[cnt]=a[i];
            cnt++;
        }
        for(i=0;i<cnt-1;i++)
            for(j=i+1;j<cnt;j++)
                if(b[i]>b[j])
                {
                    temp=b[i];
                    b[i]=b[j];
                    b[j]=temp;
                }
}

void main()
{
int i;
readDat();
jsValue();
writeDat();
printf("cnt=%d\n",cnt);
for(i=0;i<cnt;i++)
     printf("b[%d]=%d\n",i,b[i]);
}

void readDat()
{
FILE *fp;
int i;
fp=fopen("IN39.DAT","r");
for(i=0;i<300;i++)
     fscanf(fp,"%d,",&a[i]);
fclose(fp);
}

void writeDat()
{
FILE *fp;
int i;
fp=fopen("OUT39.DAT","w");
fprintf(fp,"%d\n",cnt);
for(i=0;i<cnt;i++)
    fprintf(fp, "%d\n",b[i]);
fclose(fp);
}
----------------解决方案--------------------------------------------------------
看一下
----------------解决方案--------------------------------------------------------
2#正确
isprime函数没有定义
----------------解决方案--------------------------------------------------------
知道了 谢各位 高手拉 呵呵
----------------解决方案--------------------------------------------------------