C语言中的可变参数编程

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可变参数是一种在C语言中常见且有用的编程技术,它允许函数接受不定数量的参数。这在处理具有不同参数数量的函数调用时非常方便,例如printf函数就是一个著名的可变参数函数。在本文中,我们将讨论如何在C语言中使用可变参数,并提供一些示例代码来说明其用法。

要在C语言中使用可变参数,我们需要使用C标准库中的stdarg.h头文件。该头文件定义了一些宏和类型,用于在函数中处理可变参数。

首先,让我们了解一下可变参数函数的基本原理。可变参数函数由一个固定数量的参数和一个可变数量的参数组成。固定数量的参数在函数声明中显式指定,而可变数量的参数则用省略号表示(…)。在函数体内,我们使用stdarg.h中的宏和类型来访问可变参数。

下面是一个简单的示例,演示了如何编写一个可变参数函数来计算一组整数的平均值:

#include <stdio.h>
#include <stdarg.h>

10、C语言输入输出、可变参数函数及编程思维全解析 本文深入解析了C语言中的输入输出机制与文件操作,包括常用函数如printf、fscanf和fgets的使用,并介绍了可变参数函数的实现原理。同时,文章探讨了编程中两种重要的思维方式——创造性和防御性编程,通过示例代码展示了如何编写安全、健壮的程序。最后,结合logfind工具的开发,说明了如何在实际项目中综合运用这些知识和策略。 阅读详情

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% Dropout fraction opts.numepochs = 1; % Number of full sweeps through dataopts.batchsize = 100; % Take a mean gradient step over this many samplesnn = nntrain(nn, train_x, train_y, opts);[er, bad] = nntest(nn, test_x, test_y);assert(er < 0.1, 'Too big error');%% ex4 neural net with sigmoid activation functionrand('state',0)nn = nnsetup([784 100 10]);nn.activation_function = 'sigm'; % Sigmoid activation functionnn.learningRate = 1; % Sigm require a lower learning rateopts.numepochs = 1; % Number of full sweeps through dataopts.batchsize = 100; % Take a mean gradient step over this many samplesnn = nntrain(nn, train_x, train_y, opts);[er, bad] = nntest(nn, test_x, test_y);assert(er < 0.1, 'Too big error');%% ex5 plotting functionalityrand('state',0)nn = nnsetup([784 20 10]);opts.numepochs = 5; % Number of full sweeps through datann.output = 'softmax'; % use softmax outputopts.batchsize = 1000; % Take a mean gradient step over this many samplesopts.plot = 1; % enable plottingnn = nntrain(nn, train_x, train_y, opts);[er, bad] = nntest(nn, test_x, test_y);assert(er < 0.1, 'Too big error');%% ex6 neural net with sigmoid activation and plotting of validation and training error% split training data into training and validation datavx = train_x(1:10000,:);tx = train_x(10001:end,:);vy = train_y(1:10000,:);ty = train_y(10001:end,:);rand('state',0)nn = nnsetup([784 20 10]); nn.output = 'softmax'; % use softmax outputopts.numepochs = 5; % Number of full sweeps through dataopts.batchsize = 1000; % Take a mean gradient step over this many samplesopts.plot = 1; % enable plottingnn = nntrain(nn, tx, ty, opts, vx, vy); % nntrain takes validation set as last two arguments (optionally)[er, bad] = nntest(nn, test_x, test_y);assert(er < 0.1, 'Too big error');```[![Bitdeli Badge](https://d2weczhvl823v0.cloudfront.net/rasmusbergpalm/deeplearntoolbox/trend.png)](https://bitdeli.com/free "Bitdeli Badge")

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