C语言数组问题4

//---------------------------------------------------------------------------

#include <stdio.h>
void strCat(char *a,const char *b)
{
int i,j;
for (i = 0; a[i]; i++) {}

for (j=0; b[j]; j++) {
a[i++]=b[j];
}
a[i]=0;
}
int main(void)
{
char a[120]="abc";
char b[]="def";
printf("a:\t%s\nb:\t%s\n",a,b);
strCat(a,b);
printf("a+b:\t%s\n",a);
return 0;
}
//---------------------------------------------------------------------------

#include "stdio.h"
#include "string.h"
main()
{ char a[10],b[5];
printf("enter two string:\n");
scanf("%s %s",a,b);
printf("%s",strcat(a,b));
getch();
}
想要改的话 只要改一下10和5就好了