平日小问题 (2):[Error] 'setprecision' is not a member of 'std'

本文介绍了一个使用C++模板实现通用加法功能的例子,并展示了如何通过包含正确的头文件来解决浮点数输出精度的问题。文章提供了完整的代码示例及错误修正过程。

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#include <iostream>

template <typename t>
t sum(t x,t y)
{
    return x+y;
}

int main()
{
    int a,b;
    double c,d;

    std::cin>>a>>b>>c>>d;

    std::cout<<sum(a,b)<<std::endl;
    std::cout<<std::fixed<<std::setprecision(3)<<sum(c,d)<<std::endl;
}

报错:[Error] ‘setprecision’ is not a member of ‘std’

需要加上头文件 便可通过编译

修改后:

#include <iostream>
#include <iomanip>
template <typename t>
t sum(t x,t y)
{
    return x+y;
}

int main()
{
    int a,b;
    double c,d;

    std::cin>>a>>b>>c>>d;

    std::cout<<sum(a,b)<<std::endl;
    std::cout<<std::fixed<<std::setprecision(3)<<sum(c,d)<<std::endl;
}
| set /home/lxa/repos/ns-3-allinone/ns-3.37/scratch/fanet-simplified-olsr.cc:91:27: error: ‘setw’ is not a member ofstd’; did you mean ‘set’? 91 | std::cout << std::setw(8) << std::left << "投递率(PDR)" | ^~~~ | set /home/lxa/repos/ns-3-allinone/ns-3.37/scratch/fanet-simplified-olsr.cc:92:27: error: ‘setw’ is not a member ofstd’; did you mean ‘set’? 92 | << std::setw(10) << std::fixed << std::setprecision(2) | ^~~~ | set /home/lxa/repos/ns-3-allinone/ns-3.37/scratch/fanet-simplified-olsr.cc:92:58: error:setprecisionis not a member ofstd’ 92 | << std::setw(10) << std::fixed << std::setprecision(2) | ^~~~~~~~~~~~ /home/lxa/repos/ns-3-allinone/ns-3.37/scratch/fanet-simplified-olsr.cc:94:27: error: ‘setw’ is not a member ofstd’; did you mean ‘set’? 94 | std::cout << std::setw(8) << std::left << "平均延迟" | ^~~~ | set /home/lxa/repos/ns-3-allinone/ns-3.37/scratch/fanet-simplified-olsr.cc:95:27: error: ‘setw’ is not a member ofstd’; did you mean ‘set’? 95 | << std::setw(10) << std::fixed << std::setprecision(2) | ^~~~ | set /home/lxa/repos/ns-3-allinone/ns-3.37/scratch/fanet-simplified-olsr.cc:95:58: error:setprecisionis not a member ofstd’ 95 | << std::setw(10) << std::fixed << std::setprecision(2) | ^~~~~~~~~~~~ make[3]: *** [scratch/CMakeFiles/scratch_fanet-simplified-olsr.dir/build.make:65:scratch/CMakeFiles/scratch_fanet-simplified-olsr.dir/fanet-simplified-olsr.cc.o] 错误 1 make[2]: *** [CMakeFiles/Makefile2:17732:scratch/CMakeFiles/scratch_fanet-simplified-olsr.dir/all] 错误 2 make[1]: *** [CMakeFiles/Makefile2:17738:scratch/CMakeFiles/scratch_fanet-simplified-olsr.dir/rule] 错误 2 make: *** [Makefile:5844:scratch_fanet-simplified-olsr] 错误 2
03-09
test.cpp:86:42: error: conversion from ‘Eigen::Matrix3d’ {aka ‘Eigen::Matrix<double, 3, 3>’} to non-scalar type ‘std::vector<std::vector<double> >’ requested 86 | std::vector<std::vector<double>> A = R; | ^ test.cpp:88:42: error: conversion from ‘Eigen::Matrix3f’ {aka ‘Eigen::Matrix<float, 3, 3>’} to non-scalar type ‘std::vector<std::vector<double> >’ requested 88 | std::vector<std::vector<double>> B = RR; | ^~ test.cpp:105:38: error: conflicting declaration ‘std::vector<std::vector<double> > R’ 105 | std::vector<std::vector<double>> R(3, std::vector<double>(3, 0.0)); | ^ test.cpp:32:14: note: previous declaration as ‘Eigen::Matrix3d R’ 32 | Matrix3d R; | ^ test.cpp:109:21: error: invalid types ‘Eigen::DenseCoeffsBase<Eigen::Matrix<double, 3, 3>, 1>::Scalar {aka double}[int]’ for array subscript 109 | R[i][j] += C[i][k] * temp[k][j]; | ^ test.cpp:118:45: error:setprecisionis not a member ofstd’ 118 | std::cout << std::fixed << std::setprecision(6) | ^~~~~~~~~~~~ test.cpp:119:31: error: ‘setw’ is not a member ofstd’ 119 | << std::setw(12) << R[i][j]; | ^~~~ test.cpp:119:47: error: invalid types ‘Eigen::DenseCoeffsBase<Eigen::Matrix<double, 3, 3>, 1>::Scalar {aka double}[int]’ for array subscript 119 | << std::setw(12) << R[i][j]; | ^ test.cpp:125:22: error: invalid types ‘Eigen::DenseCoeffsBase<Eigen::Matrix<double, 3, 3>, 1>::Scalar {aka double}[int]’ for array subscript 125 | double r11 = R[0][0], r12 = R[0][1], r13 = R[0][2]; | ^ test.cpp:126:22: error: invalid types ‘Eigen::DenseCoeffsBase<Eigen::Matrix<double, 3, 3>, 1>::Scalar {aka double}[int]’ for array subscript 126 | double r21 = R[1][0], r22 = R[1][1], r23 = R[1][2]; | ^ test.cpp:127:22: error: invalid types ‘Eigen::DenseCoeffsBase<Eigen::Matrix<double, 3, 3>, 1>::Scalar {aka double}[int]’ for array subscript 127 | double r31 = R[2][0], r32 = R[2][1], r33 = R[2][2]; | ^ test.cpp:130:12: error: redeclaration of ‘double pitch’ 130 | double pitch = std::atan2(-r31, std::sqrt(r32*r32 + r33*r33)); | ^~~~~ test.cpp:36:17: note: ‘double pitch’ previously declared here 36 | double yaw, pitch, roll; | ^~~~~ test.cpp:130:47: error: ‘r32’ was not declared in this scope; did you mean ‘r31’? 130 | double pitch = std::atan2(-r31, std::sqrt(r32*r32 + r33*r33)); | ^~~ | r31 test.cpp:130:57: error: ‘r33’ was not declared in this scope; did you mean ‘r31’? 130 | double pitch = std::atan2(-r31, std::sqrt(r32*r32 + r33*r33)); | ^~~ | r31 test.cpp:133:12: error: redeclaration of ‘double yaw’ 133 | double yaw = std::atan2(r21, r11); | ^~~ test.cpp:36:12: note: ‘double yaw’ previously declared here 36 | double yaw, pitch, roll; | ^~~ test.cpp:136:12: error: redeclaration of ‘double roll’ 136 | double roll = std::atan2(r32, r33); | ^~~~ test.cpp:36:24: note: ‘double roll’ previously declared here 36 | double yaw, pitch, roll; | ^~~~ In file included from /usr/include/eigen3/Eigen/Core:164, from /usr/include/eigen3/Eigen/Dense:1, from test.cpp:6: /usr/include/eigen3/Eigen/src/Core/DenseCoeffsBase.h: In instantiation of ‘Eigen::DenseCoeffsBase<Derived, 1>::Scalar& Eigen::DenseCoeffsBase<Derived, 1>::operator[](Eigen::Index) [with Derived = Eigen::Matrix<double, 3, 3>; Eigen::DenseCoeffsBase<Derived, 1>::Scalar = double; Eigen::Index = long int]’: test.cpp:109:20: required from here /usr/include/eigen3/Eigen/src/Core/DenseCoeffsBase.h:408:36: error: static assertion failed: THE_BRACKET_OPERATOR_IS_ONLY_FOR_VECTORS__USE_THE_PARENTHESIS_OPERATOR_INSTEAD 408 | EIGEN_STATIC_ASSERT(Derived::IsVectorAtCompileTime, | ^~~~~~~~~~~~~~~~~~~~~ /usr/include/eigen3/Eigen/src/Core/util/StaticAssert.h:33:54: note: in definition of macro ‘EIGEN_STATIC_ASSERT’ 33 | #define EIGEN_STATIC_ASSERT(X,MSG) static_assert(X,#MSG); | ^ /usr/include/eigen3/Eigen/src/Core/DenseCoeffsBase.h:408:36: note: ‘Eigen::Matrix<double, 3, 3>::IsVectorAtCompileTime’ evaluates to false 408 | EIGEN_STATIC_ASSERT(Derived::IsVectorAtCompileTime, | ^~~~~~~~~~~~~~~~~~~~~ /usr/include/eigen3/Eigen/src/Core/util/StaticAssert.h:33:54: note: in definition of macro ‘EIGEN_STATIC_ASSERT’ 33 | #define EIGEN_STATIC_ASSERT(X,MSG) static_assert(X,#MSG); // g++ -std=c++11 -I/usr/include/eigen3 test.cpp -o rotation_matrix #include <iostream> #include <cmath> #include <Eigen/Dense> #include <vector> using namespace Eigen; using namespace std; int main() { // 输入向量 Vector3d znew(-0.0741472, 0.321715, -0.943929); Vector3d xnew(-0.997053, 0.00682574, 0.0764145); // 1. 归一化向量 Vector3d z_unit = znew.normalized(); Vector3d x_unit = xnew.normalized(); // 2. Gram-Schmidt正交化 // 移除x_unit在z_unit方向的分量 double dot_product = x_unit.dot(z_unit); Vector3d x_ortho = x_unit - dot_product * z_unit; x_ortho.normalize(); // 3. 计算正交的y轴 Vector3d y_unit = z_unit.cross(x_ortho); y_unit.normalize(); // 4. 构建旋转矩阵 Matrix3d R; R << x_ortho, y_unit, z_unit; // 5. 计算欧拉角 (Z-Y-X顺序: yaw-pitch-roll) double yaw, pitch, roll; // 计算俯仰角 (pitch) pitch = std::asin(-R(2, 0)); // -r31 // 处理万向锁情况 (cos(pitch) ≈ 0) if (std::abs(std::cos(pitch)) > 1e-6) { yaw = std::atan2(R(1, 0), R(0, 0)); // r21, r11 roll = std::atan2(R(2, 1), R(2, 2)); // r32, r33 } else { // 万向锁时使用备用公式 yaw = std::atan2(-R(0, 1), R(1, 1)); roll = 0.0; // 横滚角自由度丢失,设为0 } // 弧度转角度 const double rad2deg = 180.0 / M_PI; yaw *= rad2deg; pitch *= rad2deg; roll *= rad2deg; // 规范化角度到[0, 360)范围 auto normalize_angle = [](double angle) { angle = std::fmod(angle, 360.0); if (angle < 0) angle += 360.0; return angle; }; yaw = normalize_angle(yaw); roll = normalize_angle(roll); // 输出结果 std::cout << "Rotation Matrix R:\n" << R << "\n\n"; std::cout << "Euler Angles (Z-Y-X order, degrees):\n"; std::cout << "Yaw (ψ): " << yaw << "°\n"; std::cout << "Pitch (θ): " << pitch << "°\n"; std::cout << "Roll (φ): " << roll << "°\n"; // 定义欧拉角 (Z-Y-X 顺序) const float yaw2 = M_PI / 2; // 绕 Z 轴 const float pitch2 = 0.0f; // 绕 Y 轴 const float roll2 = -M_PI / 2; // 绕 X 轴 // 构建旋转矩阵 (Z-Y-X 欧拉角) Eigen::Matrix3f RR; RR = Eigen::AngleAxisf(yaw2, Eigen::Vector3f::UnitZ()) * Eigen::AngleAxisf(pitch2, Eigen::Vector3f::UnitY()) * Eigen::AngleAxisf(roll2, Eigen::Vector3f::UnitX()); std::cout << "Rotation Matrix RR:\n" << RR << std::endl; std::vector<std::vector<double>> A = R; std::vector<std::vector<double>> B = RR; std::vector<std::vector<double>> C = {{-0.99595, 0.0633803, 0.0637694}, {-0.0621051, -0.997832, 0.0217865}, {0.065012, 0.0177379, 0.997727}}; // 计算 B * A std::vector<std::vector<double>> temp(3, std::vector<double>(3, 0.0)); for (int i = 0; i < 3; ++i) { for (int j = 0; j < 3; ++j) { for (int k = 0; k < 3; ++k) { temp[i][j] += B[i][k] * A[k][j]; } } } // 计算 C * temp std::vector<std::vector<double>> R(3, std::vector<double>(3, 0.0)); for (int i = 0; i < 3; ++i) { for (int j = 0; j < 3; ++j) { for (int k = 0; k < 3; ++k) { R[i][j] += C[i][k] * temp[k][j]; } } } // 输出合矩阵 std::cout << "Combined Matrix:" << std::endl; for (int i = 0; i < 3; ++i) { for (int j = 0; j < 3; ++j) { std::cout << std::fixed << std::setprecision(6) << std::setw(12) << R[i][j]; } std::cout << std::endl; } // 提取欧拉角 (ZYX顺序) double r11 = R[0][0], r12 = R[0][1], r13 = R[0][2]; double r21 = R[1][0], r22 = R[1][1], r23 = R[1][2]; double r31 = R[2][0], r32 = R[2][1], r33 = R[2][2]; // 计算pitch (Y轴) double pitch = std::atan2(-r31, std::sqrt(r32*r32 + r33*r33)); // 计算yaw (Z轴) double yaw = std::atan2(r21, r11); // 计算roll (X轴) double roll = std::atan2(r32, r33); // 转换为角度并取反 double yaw_deg = -yaw * 180.0 / M_PI; // 取反 double pitch_deg = -pitch * 180.0 / M_PI; // 取反 double roll_deg = -roll * 180.0 / M_PI; // 取反 // 角度归一化 (-180°到180°) yaw_deg = std::fmod(yaw_deg + 180.0, 360.0) - 180.0; pitch_deg = std::fmod(pitch_deg + 180.0, 360.0) - 180.0; roll_deg = std::fmod(roll_deg + 180.0, 360.0) - 180.0; // 输出修正后的欧拉角 std::cout << "\nCorrected Euler Angles (ZYX order):" << std::endl; std::cout << "Yaw (Z) : " << yaw_deg << "°" << std::endl; std::cout << "Pitch (Y) : " << pitch_deg << "°" << std::endl; std::cout << "Roll (X) : " << roll_deg << "°" << std::endl; return 0; }请修正语法
最新发布
08-16
<think>好的,我现在需要帮助用户解决在cartographer_ros的node.cpp文件中遇到的编译错误。错误是关于builtin_interfaces::msg::Time没有nsec成员以及nansec未声明的问题。首先,我得回忆一下ROS 2中的时间类型结构。 用户提到他们之前引用了ROS 1中的时间类型,但问题出在ROS 2中。因为在ROS 2里,builtin_interfaces::msg::Time的结构可能与ROS 1不同。ROS 1中的时间结构确实有sec和nsec成员,但ROS 2可能有所变化。我需要确认ROS 2的Time消息的具体定义。 查阅ROS 2的文档,builtin_interfaces/msg/Time确实包含两个字段:sec和nanosec。这可能就是问题的根源。用户可能在代码中错误地使用了nsec或nansec,而正确的成员名称应该是nanosec。例如,正确的访问方式应该是time.sec和time.nanosec。 接下来,我需要检查用户代码中哪里用到了nsec或nansec。比如,可能在构造Time消息时,错误地指定了nsec字段,而应该使用nanosec。或者,在从现有Time对象中读取纳秒部分时,错误地引用了nsec而不是nanosec。 例如,用户可能有这样的代码: builtin_interfaces::msg::Time timestamp; timestamp.sec = 123; timestamp.nsec = 456; // 错误,正确应为nanosec 或者在使用类似函数时,参数名可能不同。另外,可能用户将nanosec拼写成了nansec,导致未声明的错误。 因此,解决方案应该是将代码中所有用到nsec或nansec的地方替换为nanosec。同时,检查是否有拼写错误,比如是否漏掉了中间的字母o,写成nansec而不是nanosec。 另外,还需要提醒用户注意ROS 2和ROS 1在API上的差异,特别是在时间处理部分。在ROS 2中,客户端库可能统一了命名,避免像ROS 1中C++和Python的不同命名问题。因此,用户需要根据ROS 2的API进行相应的调整。 总结步骤: 1. 查找node.cpp中使用builtin_interfaces::msg::Time的地方。 2. 将所有访问nsec或nansec的代码改为使用nanosec。 3. 确保sec字段正确使用,没有拼写错误。 4. 编译并测试修改后的代码,确认错误是否解决。 可能还需要用户检查是否有其他依赖部分也使用了错误的时间成员,比如其他消息类型或函数参数。此外,如果用户是从ROS 1迁移到ROS 2,可能需要全面检查时间相关的代码,因为这种差异可能导致多处错误。</think>根据ROS 2时间类型定义,`builtin_interfaces::msg::Time`的正确成员变量是`sec`和`nanosec`(注意完整拼写),需按以下步骤修改: 1. **替换成员变量名称** ```cpp // 原错误代码(假设存在): builtin_interfaces::msg::Time timestamp; timestamp.nsec = ...; // 错误形式 // 修改为: timestamp.nanosec = ...; // 正确形式[^1] ``` 2. **处理时间构造场景** ```cpp // 创建时间戳的正确方式: const int64_t nanoseconds = ...; const auto timestamp = rclcpp::Time(seconds * 1e9 + nanoseconds).to_msg(); // 使用标准时间转换接口 ``` 3. **检查未声明标识符** 若出现`nansec`未声明错误,需确认是否拼写错误,正确拼写应为`nanosec`(包含中间的字母o)
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