Dev C++ Switch Example
C Tutorial – Learn C Programming with examples By Chaitanya Singh Filed Under: Learn C C language is a direct descendant of C programming language with additional features such as type checking, object oriented programming, exception handling etc. C: Switch Statements Sometimes when creating a C program, you run into a situation in which you want to compare one thing to a number of other things. Let's say, for example, that you took a character from the user and wanted to compare this to a number of characters to perform different actions. A switch statement allows a variable to be tested for equality against a list of values. Each value is called a case, and the variable being switched on is checked for each case. The syntax for a switch statement in C is as follows −.
Cooking mama nintendo ds free download. I have to confess that I did not read thru this discussions since I'm really happy with the solution demonstrated, which has proven its usability in real life. But I do not want to give the impression that I was the first and only one who had the idea of using a map to implement switch on strings in C. About the Author. A switch statement allows a variable to be tested for equality against a list of values. Each value is called a case, and the variable being switched on is checked for each switch case. The syntax for a switch statement in C programming language is as follows −. Dec 21, 2008 Using Range in the Case Values of Switch Statement C Programming Video Tutorial - Duration: 12:07. LearningLad 16,202 views. Shapes in c using nested loops and pattern.
The switch statement in C++ is a control statement that is useful in a limited number of cases. The switch statement resembles a compound if statement by including a number of different possibilities rather than a single test:
The value of expression must be an integer (int, long, or char). The case values must be constants.
As of the ‘14 standard, they can also be a constant expression.
When the switch statement is encountered, the expression is evaluated and compared to the various case constants. Control branches to the case that matches. If none of the cases match, control passes to the default clause.
Consider the following example code snippet:
Once again, the switch statement has an equivalent; in this case, multiple if statements. However, when there are more than two or three cases, the switch structure is easier to understand.
The break statements are necessary to exit the switch command. Without the break statements, control falls through from one case to the next. (Look out below!)
| /* |
| needs libmosquitto-dev |
| $ gcc -o libmosq libmosq.c -lmosquitto |
| */ |
| #include<stdio.h> |
| #include<mosquitto.h> |
| #include<stdlib.h> |
| #include<string.h> |
| #include<unistd.h> |
| voidmosq_log_callback(struct mosquitto *mosq, void *userdata, int level, constchar *str) |
| { |
| /* Pring all log messages regardless of level. */ |
| switch(level){ |
| //case MOSQ_LOG_DEBUG: |
| //case MOSQ_LOG_INFO: |
| //case MOSQ_LOG_NOTICE: |
| case MOSQ_LOG_WARNING: |
| case MOSQ_LOG_ERR: { |
| printf('%i:%sn', level, str); |
| } |
| } |
| } |
| struct mosquitto *mosq = NULL; |
| char *topic = NULL; |
| voidmqtt_setup(){ |
| char *host = 'localhost'; |
| int port = 1883; |
| int keepalive = 60; |
| bool clean_session = true; |
| topic = '/testtopic'; |
| mosquitto_lib_init(); |
| mosq = mosquitto_new(NULL, clean_session, NULL); |
| if(!mosq){ |
| fprintf(stderr, 'Error: Out of memory.n'); |
| exit(1); |
| } |
| mosquitto_log_callback_set(mosq, mosq_log_callback); |
| if(mosquitto_connect(mosq, host, port, keepalive)){ |
| fprintf(stderr, 'Unable to connect.n'); |
| exit(1); |
| } |
| int loop = mosquitto_loop_start(mosq); |
| if(loop != MOSQ_ERR_SUCCESS){ |
| fprintf(stderr, 'Unable to start loop: %in', loop); |
| exit(1); |
| } |
| } |
| intmqtt_send(char *msg){ |
| returnmosquitto_publish(mosq, NULL, topic, strlen(msg), msg, 0, 0); |
| } |
| intmain(int argc, char *argv[]) |
| { |
| mqtt_setup(); |
| int i = -1000; |
| char *buf = malloc(64); |
| while(1){ |
| sprintf(buf,'i=%i',i++); |
| int snd = mqtt_send(buf); |
| if(snd != 0) printf('mqtt_send error=%in', snd); |
| usleep(100000); |
| } |
| } |
commented May 30, 2019
how to subscribe? |
commented May 30, 2019 • edited
edited
looks like message_callback hm.. do you know good example? official docs seems suxx |
commented May 30, 2019
Switch Dev C++ Example
looks better example: https://gist.github.com/evgeny-boger/8cefa502779f98efaf24 |
