变量‘std::istringstream stream’有初始值设定,但是类型不完全

博客指出在遇到初始值设定但类型不完全的问题时,可检查是否忘记包含 <sstream> 头文件,这是信息技术编程中解决类型相关问题的一个要点。

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检查是不是头文件忘记了

#include<sstream>

#define _CRT_SECURE_NO_WARNINGS 1 #define _CSIDL_DESKTOPDIRECTORY 1 #include <stdio.h> #include <Shlobj.h> #include <iostream> #include <fstream> #include <string> #include <vector> #include <sstream> #include <windows.h> // 获取桌面路径函数 std::string GetDesktopPath() { char desktopPath[MAX_PATH]; if (SUCCEEDED(SHGetFolderPathA(NULL, CSIDL_DESKTOPDIRECTORY, NULL, 0, desktopPath))) { return std::string(desktopPath) + "\\"; } return ""; } int main() { // 获取桌面路径 std::string desktopPath = GetDesktopPath(); if (desktopPath.empty()) { std::cerr << "无法获取桌面路径!" << std::endl; return 1; } // 输入输出文件名 std::string inputFile = desktopPath + "input.txt"; std::string outputFile = desktopPath + "output.csv"; // 打开输入文件 std::ifstream inFile(inputFile); if (!inFile.is_open()) { std::cerr << "无法打开输入文件: " << inputFile << std::endl; return 1; } // 创建输出文件 std::ofstream outFile(outputFile); if (!outFile.is_open()) { std::cerr << "无法创建输出文件: " << outputFile << std::endl; return 1; } std::string line; // 写入CSV表头 outFile << "S,V,C,LPump,RPump,\n"; // 处理每行数据 while (std::getline(inFile, line)) { std::istringstream iss(line); int R_Pump = 0, score; std::string name; char comma; // 解析数据 (格式: ID,Name,Score) if (iss >> id >> comma && std::getline(iss, name, ',') >> score) { // 添加额外处理逻辑(示例:计算等级) std::string grade = (score >= 90) ? "A" : (score >= 80) ? "B" : "C"; // 写入CSV行 outFile << id << "," << name << "," << score << "," << grade << "\n"; } } // 关闭文件 inFile.close(); outFile.close(); std::cout << "数据处理完成! 输出文件: " << outputFile << std::endl; return 0; } 在这个代码更改
06-29
#include <iostream> #include <cmath> #include <chrono> #include <thread> #include <vector> #include <gmpxx.h> #include <fstream> #include <sstream> #include <iomanip> #include <mutex> #include <atomic> #include <sys/sysinfo.h> #include <sys/resource.h> #include <fstream> #include <unistd.h> #include <nvml.h> // NVIDIA GPU监控 std::mutex output_mutex; std::atomic<bool> stop_monitor(false); mpf_class pi_value(0, 0); // 高精度π值 std::atomic<int> iteration_count(0); // 获取CPU使用率 double get_cpu_usage() { static uint64_t last_total = 0, last_idle = 0; std::ifstream stat_file("/proc/stat"); std::string line; std::getline(stat_file, line); std::istringstream iss(line); std::string cpu; uint64_t user, nice, system, idle, iowait, irq, softirq, steal; iss >> cpu >> user >> nice >> system >> idle >> iowait >> irq >> softirq >> steal; uint64_t total = user + nice + system + irq + softirq + steal; uint64_t idle_time = idle + iowait; double usage = 0.0; if (last_total != 0) { uint64_t total_diff = total - last_total; uint64_t idle_diff = idle_time - last_idle; usage = 100.0 * (1.0 - static_cast<double>(idle_diff) / total_diff); } last_total = total; last_idle = idle_time; return usage; } // 获取内存使用率 double get_memory_usage() { struct sysinfo mem_info; sysinfo(&mem_info); double total = mem_info.totalram; double free = mem_info.freeram; return 100.0 * (1.0 - free / total); } // 获取GPU使用率 (NVIDIA) double get_gpu_usage() { nvmlReturn_t result; nvmlDevice_t device; unsigned int utilization; result = nvmlInit(); if (result != NVML_SUCCESS) return -1.0; result = nvmlDeviceGetHandleByIndex(0, &device); if (result != NVML_SUCCESS) { nvmlShutdown(); return -1.0; } result = nvmlDeviceGetUtilizationRates(device, &utilization); if (result != NVML_SUCCESS) { nvmlShutdown(); return -1.0; } nvmlShutdown(); return static_cast<double>(utilization.gpu); } // 资源监控线程函数 void monitor_resources() { while (!stop_monitor) { double cpu = get_cpu_usage(); double mem = get_memory_usage(); double gpu = get_gpu_usage(); { std::lock_guard<std::mutex> lock(output_mutex); std::cout << "\033[2K"; // 清除当前行 std::cout << "\r[资源监控] CPU: " << std::fixed << std::setprecision(1) << cpu << "% | " << "内存: " << mem << "% | " << "GPU: " << (gpu >= 0 ? std::to_string(static_cast<int>(gpu)) + "%" : "N/A"); std::cout.flush(); } std::this_thread::sleep_for(std::chrono::seconds(1)); } } // Chudnovsky算法计算π mpf_class chudnovsky_pi(unsigned int precision, unsigned int iterations) { mpf_set_default_prec(precision); mpf_class pi(0, precision); mpf_class sum(0, precision); mpf_class k1(13591409, precision); mpf_class k2(545140134, precision); mpf_class k3(-262537412640768000, precision); mpf_class k4(426880, precision); mpf_class k5(10005, precision); mpf_class sqrt_c(0, precision); k5 = sqrt(k5); sqrt_c = k4 * k5; mpz_class a(1); mpz_class b(1); mpz_class a_prime(1); mpz_class b_prime(1); for (unsigned int k = 0; k < iterations; k++) { mpf_class numerator(0, precision); mpf_class denominator(0, precision); if (k == 0) { a = 1; b = 1; } else { // 使用二进制分裂法优化计算 a_prime = (6*k-5)*(2*k-1)*(6*k-1); b_prime = k*k*k * k3 / 24; a *= a_prime; b *= b_prime; } numerator = k1 + k2 * k; denominator = a * b; sum += numerator / denominator; iteration_count = k + 1; // 每100次迭代显示进度 if (k % 100 == 0) { pi = sqrt_c / sum; std::lock_guard<std::mutex> lock(output_mutex); std::cout << "\n[计算进度] 迭代: " << k << "/" << iterations << " | 当前π值: " << std::setprecision(15) << pi << std::endl; } } pi = sqrt_c / sum; return pi; } int main() { const unsigned int precision = 100000; // 二进制精度位 const unsigned int iterations = 1000; // 迭代次数 std::cout << "开始计算π值 (Chudnovsky算法)..." << std::endl; std::cout << "精度: " << precision << "位 | 最大迭代: " << iterations << std::endl; // 启动资源监控线程 std::thread monitor_thread(monitor_resources); // 记录开始时间 auto start_time = std::chrono::high_resolution_clock::now(); // 计算π值 pi_value = chudnovsky_pi(precision, iterations); // 记录结束时间 auto end_time = std::chrono::high_resolution_clock::now(); auto duration = std::chrono::duration_cast<std::chrono::milliseconds>(end_time - start_time); // 停止监控线程 stop_monitor = true; monitor_thread.join(); // 输出最终结果 std::cout << "\n\n计算完成!" << std::endl; std::cout << "耗时: " << duration.count() / 1000.0 << " 秒" << std::endl; std::cout << "最终π值(前50位): " << std::setprecision(50) << pi_value << std::endl; return 0; } 修复代码错误 default.cpp:6:10: fatal error: 'gmpxx.h' file not found #include <gmpxx.h> ^~~~~~~~~ 1 error generated.
最新发布
07-25
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