我有这个最小的代码
vector当我在第二个循环中打印public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.println("Skriv inn fornavn: ");
String fornavn = scanner.nextLine();
System.out.println("Skriv inn etternavn: ");
String etternavn = scanner.nextLine();
System.out.println("Skriv inn alder: ");
int alder = scanner.nextLine();
System.out.println("Ditt navn er: " + fornavn + " " + etternavn);
System.out.println("Din alder er: " + alder);
}
时得到
编号：1编号：2编号：54
有人可以告诉我为什么输出不是
编号：1.0编号：2.0编号：54.0
因为它们不再是整数，否则将与#include <iostream>
#include <string>
#include <random>
int main() {
std::vector<std::double_t> rationalNumbers;
std::vector<std::string> input {"1", "2", "54"};
for (auto &st : input)
{
rationalNumbers.push_back((std::double_t) std::stod(st));
}
for (auto &number : rationalNumbers)
{
std::cout << "Number: " << number << std::endl;
}
}
冲突，或者我错了吗？
答案 0 :(得分：2)
您的问题基于一个错误的前提，即流式传输浮点类型的值会自动为您保留一位小数。它没有，而且从来没有。
您将类型/表格与表示形式混淆。在某些情况下，假设整数1与浮点值1.0相同，则显示整数std::fixed是完全合理的。
要获取定点表示，可以使用def checar_valor(a,b):
for i in range(len(a)):
if b.isin([a['File'][i]]): #ERROR
print("O valor %s está presente nos dois dataframes" % a['File'][i])
else:
print("O valor %s está presente apenas no dataframe %s" % (a['File'][i], "a"))
for q in range(len(b)):
if a.isin([b['Código da transação'][q]]): #ERROR
print("O valor %s está presente nos dois dataframes" % b['Código da transação'][q])
else:
print("O valor %s está presente apenas no dataframe %s" % (b['Código da transação'][q], "b"))
Traceback (most recent call last):
File "C:/Users/nick/PycharmProjects/WebCrawler/Extranet/testezin.py", line 75, in <module>
checar_valor(rs, ga)
File "C:/Users/nick/PycharmProjects/WebCrawler/Extranet/testezin.py", line 64, in checar_valor
if b.isin([a['File'][i]]): #ERRO
File "C:\Users\nick\PycharmProjects\WebCrawler\venv\lib\site-packages\pandas\core\generic.py", line 1576, in __nonzero__
.format(self.__class__.__name__))
ValueError: The truth value of a DataFrame is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
。或探索其他一些I/O manipulators。最终，此数字的呈现方式取决于您。