#include <stdio.h>
double clear(double sum,double value)
{
    int num;
    double newsum;
    
    num=(int)(sum/value);
    if (value>1)
        printf("%f元%d张\n",value,num);
    else
        printf("%f角%d张\n",value*10,num); 
    newsum=sum-value*num;
    return newsum;    
} 
int main(void)
{
    double clear(double sum,double value);
    double sum;
    double money[7]={100,50,10,5,0.5,0.1};
    printf("请输入实发工资总额\n");
    scanf("%f",&sum);
    for (int i=0;i<=5;i++)
    {
        sum=clear(sum,money[i]);
    }
}

谢谢你回的那么快，
我哪本书问题也不少啊。
可是改过之后我又发现一个问题：
#include <stdio.h>
double clear(double sum,double value)
{
    int num;
    double newsum;
   
    num=(int)(sum/value);
    if (value>1)
        printf("%lf元%d张\n",value,num);
    else
        printf("%f角%d张\n",value*10,num);
    newsum=sum-value*num;
    return newsum;   
}
int main(void)
{
    double clear(double sum,double value);
    double sum;
    double money[6]={100,50,10,5,0.5,0.1};
    printf("请输入实发工资总额\n");
    scanf("%lf",&sum);
    for (int i=0;i<=5;i++)
    {
        sum=clear(sum,money[i]);
    }
}

少了1角，是数据处理的问题吗。
再次谢谢你的回复