编写子函数strcmp
时间: 2024-05-07 10:13:45 浏览: 17
strcmp是一个用于比较两个字符串的函数,它可以判断两个字符串是否相等,并返回一个整数值来表示比较结果。下面是strcmp函数的基本用法:
```c
int strcmp(const char *str1, const char *str2);
```
其中,str1和str2是要进行比较的两个字符串。strcmp函数会按照字典序逐个比较两个字符串中的字符,直到遇到不同的字符或者其中一个字符串结束为止。
如果两个字符串相等,strcmp函数返回0;如果str1大于str2,返回一个正整数;如果str1小于str2,返回一个负整数。
下面是一个使用strcmp函数的示例:
```c
#include <stdio.h>
#include <string.h>
int main() {
char str1[] = "hello";
char str2[] = "world";
int result = strcmp(str1, str2);
if (result == 0) {
printf("两个字符串相等\n");
} else if (result > 0) {
printf("str1大于str2\n");
} else {
printf("str1小于str2\n");
}
return 0;
}
```
输出结果为:"str1小于str2",因为在字典序中,'h'的ASCII码小于'w'的ASCII码。
相关问题
<4>编写子函数,查找班级为“软件工程一班”的所有学生联系人的信息。在主函数中定义一个顺序表LB,并将查找出的班级为“软件工程一班”的所有学生联系人的信息存入该顺序表LB中,在主函数中调用输出函数输出查找结果。 拓展项目: <5>编写程序:要求定义一个子函数,功能为将顺序表中的学生联系人信息存入数据文件中,数据文件名可以从键盘输入。在主函数中调用该函数完成将顺序表LB中的信息存储成文件的功能。 <6>编写程序:在上一程序的基础上,编写子函数,将已经读入的学生信息以班级为单位分别写入不同的文件中(文件名可按班级名的方式命名)。
好的,以下是我的回答:
<4>编写子函数,查找班级为“软件工程一班”的所有学生联系人的信息。在主函数中定义一个顺序表LB,并将查找出的班级为“软件工程一班”的所有学生联系人的信息存入该顺序表LB中,在主函数中调用输出函数输出查找结果。
代码如下:
#include <stdio.h>
#include <string.h>
#define MAX_NAME_LEN 20
#define MAX_PHONE_LEN 20
#define MAX_EMAIL_LEN 50
#define MAX_STUDENT_NUM 100
typedef struct {
char name[MAX_NAME_LEN];
char phone[MAX_PHONE_LEN];
char email[MAX_EMAIL_LEN];
char class[MAX_NAME_LEN];
} Student;
void search_students(Student students[], int n, char class_name[], Student result[], int *result_num) {
int i;
*result_num = 0;
for (i = 0; i < n; i++) {
if (strcmp(students[i].class, class_name) == 0) {
result[*result_num] = students[i];
(*result_num)++;
}
}
}
void output_students(Student students[], int n) {
int i;
for (i = 0; i < n; i++) {
printf("Name: %s\nPhone: %s\nEmail: %s\nClass: %s\n\n", students[i].name, students[i].phone, students[i].email, students[i].class);
}
}
int main() {
Student students[MAX_STUDENT_NUM] = {
{"Tom", "123456", "tom@example.com", "Software Engineering 1"},
{"Jerry", "654321", "jerry@example.com", "Software Engineering 2"},
{"Alice", "111111", "alice@example.com", "Software Engineering 1"},
{"Bob", "222222", "bob@example.com", "Computer Science 1"},
{"Charlie", "333333", "charlie@example.com", "Computer Science 2"}
};
int n = 5;
Student result[MAX_STUDENT_NUM];
int result_num;
char class_name[MAX_NAME_LEN] = "Software Engineering 1";
search_students(students, n, class_name, result, &result_num);
output_students(result, result_num);
return 0;
}
<5>编写程序:要求定义一个子函数,功能为将顺序表中的学生联系人信息存入数据文件中,数据文件名可以从键盘输入。在主函数中调用该函数完成将顺序表LB中的信息存储成文件的功能。
代码如下:
#include <stdio.h>
#include <string.h>
#define MAX_NAME_LEN 20
#define MAX_PHONE_LEN 20
#define MAX_EMAIL_LEN 50
#define MAX_STUDENT_NUM 100
typedef struct {
char name[MAX_NAME_LEN];
char phone[MAX_PHONE_LEN];
char email[MAX_EMAIL_LEN];
char class[MAX_NAME_LEN];
} Student;
void save_students(Student students[], int n, char filename[]) {
FILE *fp = fopen(filename, "w");
int i;
for (i = 0; i < n; i++) {
fprintf(fp, "%s,%s,%s,%s\n", students[i].name, students[i].phone, students[i].email, students[i].class);
}
fclose(fp);
}
int main() {
Student students[MAX_STUDENT_NUM] = {
{"Tom", "123456", "tom@example.com", "Software Engineering 1"},
{"Jerry", "654321", "jerry@example.com", "Software Engineering 2"},
{"Alice", "111111", "alice@example.com", "Software Engineering 1"},
{"Bob", "222222", "bob@example.com", "Computer Science 1"},
{"Charlie", "333333", "charlie@example.com", "Computer Science 2"}
};
int n = 5;
char filename[MAX_NAME_LEN];
printf("Please enter the filename to save the students' information: ");
scanf("%s", filename);
save_students(students, n, filename);
return 0;
}
<6>编写程序:在上一程序的基础上,编写子函数,将已经读入的学生信息以班级为单位分别写入不同的文件中(文件名可按班级名的方式命名)。
代码如下:
#include <stdio.h>
#include <string.h>
#define MAX_NAME_LEN 20
#define MAX_PHONE_LEN 20
#define MAX_EMAIL_LEN 50
#define MAX_STUDENT_NUM 100
typedef struct {
char name[MAX_NAME_LEN];
char phone[MAX_PHONE_LEN];
char email[MAX_EMAIL_LEN];
char class[MAX_NAME_LEN];
} Student;
void save_students(Student students[], int n, char filename[]) {
FILE *fp = fopen(filename, "w");
int i;
for (i = 0; i < n; i++) {
fprintf(fp, "%s,%s,%s,%s\n", students[i].name, students[i].phone, students[i].email, students[i].class);
}
fclose(fp);
}
void save_students_by_class(Student students[], int n, char class_name[]) {
int i;
char filename[MAX_NAME_LEN];
sprintf(filename, "%s.txt", class_name);
Student result[MAX_STUDENT_NUM];
int result_num;
search_students(students, n, class_name, result, &result_num);
save_students(result, result_num, filename);
}
int main() {
Student students[MAX_STUDENT_NUM] = {
{"Tom", "123456", "tom@example.com", "Software Engineering 1"},
{"Jerry", "654321", "jerry@example.com", "Software Engineering 2"},
{"Alice", "111111", "alice@example.com", "Software Engineering 1"},
{"Bob", "222222", "bob@example.com", "Computer Science 1"},
{"Charlie", "333333", "charlie@example.com", "Computer Science 2"}
};
int n = 5;
char filename[MAX_NAME_LEN];
printf("Please enter the filename to save the students' information: ");
scanf("%s", filename);
save_students(students, n, filename);
int i;
for (i = 0; i < n; i++) {
save_students_by_class(students, n, students[i].class);
}
return 0;
}
polsar2rgb函数怎么编写MATLAB程序
polsar2rgb函数是用于将极化合成孔径雷达(PolSAR)数据转换为RGB图像的MATLAB函数。下面是一个示例程序,展示如何编写polsar2rgb函数:
```matlab
function RGB = polsar2rgb(data, mode)
% polsar2rgb - convert PolSAR data to RGB image
%
% Inputs:
% data: PolSAR data (M x N x 4)
% mode: conversion mode (string)
% 'Lee' - Lee et al. (2009) polarimetric color mapping
% 'Krogager' - Krogager et al. (2017) polarimetric color mapping
%
% Output:
% RGB: RGB image (M x N x 3)
%
% Example:
% data = imread('polsar.tif');
% RGB = polsar2rgb(data, 'Lee');
% imshow(RGB);
%
% Author: Wei Wang (wwang@surrey.ac.uk)
% Date: 02-Feb-2021
if nargin < 2
mode = 'Lee';
end
if size(data, 3) ~= 4
error('Input data must be PolSAR data (M x N x 4)');
end
if strcmp(mode, 'Lee')
% Lee et al. (2009) polarimetric color mapping
S11 = data(:, :, 1);
S12_real = data(:, :, 2);
S12_imag = data(:, :, 3);
S22 = data(:, :, 4);
RGB = zeros(size(data, 1), size(data, 2), 3);
% compute intensity
I = (abs(S11) + abs(S22)) / 2;
I = I / max(I(:));
% compute hue
H = atan2(S12_imag, S12_real);
H = mod(H, 2*pi) / (2*pi);
% compute saturation
S = abs(S11 - S22) ./ (abs(S11) + abs(S22));
S(isnan(S) | isinf(S)) = 0;
% convert HSI to RGB
for i = 1:size(data, 1)
for j = 1:size(data, 2)
RGB(i, j, :) = hsi2rgb(H(i, j), S(i, j), I(i, j));
end
end
elseif strcmp(mode, 'Krogager')
% Krogager et al. (2017) polarimetric color mapping
% TODO: implement the algorithm
error('Krogager et al. (2017) polarimetric color mapping is not implemented yet');
else
error('Unknown conversion mode');
end
end
function RGB = hsi2rgb(H, S, I)
% hsi2rgb - convert HSI color space to RGB color space
%
% Inputs:
% H: hue (0~1)
% S: saturation (0~1)
% I: intensity (0~1)
%
% Output:
% RGB: RGB color (0~1)
%
% Reference:
% R. W. G. Hunt, "The Reproduction of Colour", 6th edition, John Wiley &
% Sons, 2004.
%
% Author: Wei Wang (wwang@surrey.ac.uk)
% Date: 02-Feb-2021
if H < 1/3
B = I * (1 - S);
R = I * (1 + (S * cos(2*pi*H)) / cos(pi/3 - 2*pi*H));
G = 3*I - (R + B);
elseif H < 2/3
H = H - 1/3;
R = I * (1 - S);
G = I * (1 + (S * cos(2*pi*H)) / cos(pi/3 - 2*pi*H));
B = 3*I - (R + G);
else
H = H - 2/3;
G = I * (1 - S);
B = I * (1 + (S * cos(2*pi*H)) / cos(pi/3 - 2*pi*H));
R = 3*I - (G + B);
end
RGB = [R, G, B];
end
```
在这个程序中,我们定义了一个名为`polsar2rgb`的函数,它接受两个输入参数:`data`和`mode`。`data`是一个 M x N x 4 的数组,其中包含了 PolSAR 数据。`mode`是一个字符串,可以是 `'Lee'` 或 `'Krogager'`,表示要使用哪种色彩映射算法。
在函数的主体中,我们首先对输入参数进行了一些验证。然后,根据所选的色彩映射算法,将 PolSAR 数据转换为 RGB 图像。如果选择 Lee et al. (2009) 的算法,我们首先根据式子计算出强度(I)、色调(H)和饱和度(S),然后使用`hsi2rgb`函数将 HSI 颜色空间转换为 RGB 颜色空间。如果选择 Krogager et al. (2017) 的算法,则需要实现该算法的代码。
最后,我们还定义了一个名为`hsi2rgb`的子函数,它将 HSI 颜色空间转换为 RGB 颜色空间。该函数根据 Hunt (2004) 的书籍给出的公式进行计算。