gpt4 book ai didi

c - 使用scanf()输入字符的问题

转载 作者:太空狗 更新时间:2023-10-29 15:43:28 27 4
gpt4 key购买 nike

我正在尝试将一个字符输入到链表中,其中字符可以是 'A'、'a'、'G'、'g'、'T'、't'、'C' 或 ' c'.

我还不熟悉 C,但我知道我在这里搞砸了:

do{
printf ("\nEnter a new nucleotide: \n");
scanf("%c",&newChar);
/* Checking */
if(newChar == 'A' ||
newChar == 'a' ||
newChar == 'G' ||
newChar == 'g' ||
newChar == 'T' ||
newChar == 't' ||
newChar == 'C' ||
newChar == 'c' )
{
AddToSequence(newChar);
size++;
} else {
printf ("\nBad Element");
}
}while(newChar != 'x');

newChar 使用垃圾值初始化,在本例中为“q”。

输入“x”退出循环,输入任何可接受的值调用 AddToSequence(),任何 Not Acceptable 值都会收到警告。

由于某种原因,无论newChar中有什么值,都会跳转到else。它还会直接跳过 scanf 而无需等待用户输入,并且每次循环时都会执行两个循环。谁能告诉我哪里出错了?

完整程序:

#include<stdio.h>
#include<stdlib.h>

/*Structure declaration for the node*/
struct node{
char nucleotide;
struct node *point;
}*start;

/* Adds a nucleotide to the chain. Creates a new linked list if no chain exists exists.*/
void AddToSequence(char nucleotide){
struct node *loc, *first;
//Dynamic memory is been allocated for a node
first=(struct node*)malloc(sizeof(struct node));
first->nucleotide=nucleotide;
first->point=NULL;
if(start==NULL){
/*If list is empty*/
start=first;
}else{
/*Element inserted at the end*/
loc=start;
while(loc->point!=NULL){
loc=loc->point;
loc->point=first;
}
}
}

/* Display elements */
void Display(){
struct node *loc;
if(start == NULL){
printf ("\n\nList is empty");
return;
}
loc=start;
printf("\n\nList is : ");
while(loc!=NULL){
printf ("%c", loc->nucleotide);
loc=loc->point;
}
printf ("\n");
}

/* Finds and displays percentage of the chain made up of each nucleotide. */
void Percentage(int size){
struct node *loc;
if(start == NULL){
printf ("\n\nList is empty");
return;
}
loc=start;
printf("\n\nList is : ");
int A = 0, G =0, T =0, C = 0;
double Adouble = 0, Gdouble =0, Tdouble=0, Cdouble=0;
while(loc!=NULL){
if(loc->nucleotide=='A' || 'a'){A++;}
if(loc->nucleotide=='G' || 'g'){G++;}
if(loc->nucleotide=='T' || 't'){T++;}
if(loc->nucleotide=='C' || 'c'){C++;}
loc=loc->point;
}
printf ("\n");

/* Convert to double for percentages as int loses precision */
Adouble =A;
Gdouble =G;
Tdouble =T;
Cdouble =C;
Adouble =(Adouble/size)*100;
Gdouble =(Gdouble/size)*100;
Tdouble =(Tdouble/size)*100;
Cdouble =(Cdouble/size)*100;
printf("\nA: %f", Adouble);
printf("\nG: %f", Gdouble);
printf("\nT: %f", Tdouble);
printf("\nC: %f", Cdouble);
}

/* There be dragons beyond here */
int main(){
int navigate, size =0;
char newChar = 'q';
do{ /* Menu */
printf("\n 1. Create / Extend Sequence\n");
printf("\n 2. Display Sequence\n");
printf("\n 3. Count \n");
printf("\n 0. Exit \n");
printf("\nPlease select an option (0 to 3)\n");
scanf("%d",&navigate);
switch (navigate){
case 0: /* Exit */
break;
case 1: /* Add nucleotides */
do{
printf ("\nEnter a new nucleotide: \n");
scanf("%c",&newChar);
/* Some error checking */
if(newChar == 'A' || newChar == 'a' || newChar == 'G' || newChar == 'g' || newChar == 'T' || newChar == 't' || newChar == 'C' || newChar == 'c' ){
AddToSequence(newChar);
size++;
} else {
printf ("\nBad Element");
}
}while(newChar != 'x');
break;
case 2:
Display();
break;
case 3:
Percentage(size);
break;
default:
printf ("\n\nBad choice. Please select another.\n");
}
} while (navigate !=0);
return 0 ;
}

最佳答案

您不处理换行符。 %c 说明符不会跳过空格。尝试:

scanf(" %c", &newChar);
/* ^ <-- Makes `scanf` eat the newline. */

或者添加一个显式测试。

scanf(...);
if (newChar == '\n')
continue;

关于c - 使用scanf()输入字符的问题,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13710867/

27 4 0
Copyright 2021 - 2024 cfsdn All Rights Reserved 蜀ICP备2022000587号
广告合作:1813099741@qq.com 6ren.com