删除字符串中多余的空格

"    we   are  happy.   "变为“we are happy.”

#include<stdio.h>

void deleteBlank(char* a);
int main()
{
char a[100]="    we   are  happy.   ";
deleteBlank(a);
printf("%s",a);
}
void deleteBlank(char* a)
{
int i,j;
if(a==NULL)
return;
  
i=0;
j=0;


while(a[j]!='\0')
{
while(a[j]==' ')
   j++;
while(a[j]!=' ' && a[j]!='\0')
a[i++]=a[j++];
a[i++]=a[j];
}
a[i]='\0';

}