C Primer Plus 中关于*修饰符（抑制赋值）的一些总结

printf()中的抑制赋值

当转换说明是%d那么参数列表应该包括和d对应的值（这个技巧也适用于浮点值指定精度和字段宽度
printf()函数的返回值是返回打印字符的个数

示例

#include<stdio.h>
#define  ATOM "He's a Trisolaran!"
int main(void){
    int litho;
    int width=9;
    int core=4;
    double hydro =123.45;
    printf("%*d\n",core,width);
    printf("%*.*lf\n",width,core,hydro);
    litho=printf("%s\n",ATOM);
    printf("%d characters\n",litho);
    return 0;
}

scanf()中的抑制赋值

把*放在%和转换字符之间时会使得scanf()跳过相应的输出项
scanf()函数返回成功读取的项数

示例

#include<stdio.h>
int main(void){
    int n;
    scanf("%*d %*d %d",&n);
    printf("The last character is %d\n",n);  //把*放在%和d之间会使得scanf跳过相应的输出项
    return 0;
    }
    

在比姓名宽度宽3的字段中打印名字

示例

#include<stdio.h>
#include<string.h>
int main(void){
    char name[15] ;
    char surname[15];
    printf("Please enter your name:\n");
    scanf("%s %s",name,surname);
    printf("Yeah!Your name is \"%s,%s\"\n",name,surname);
    printf("\"%20s\"\n",name);
    printf("\"%-20s\"\n",name);
    printf("\"%*s\"",(int)strlen(name)+3,name);//这里int为强制转换不进行强制转换会出现警告Field width should have type 'int', but argument has type 'unsigned long'
    return 0;
}