how to cast int from int[] to const char*

Question

like the topic mention.... for example

int[10] msg;

msg[0] = 1;
msg[1] = 2;

const char* a = (const char*)msg[0];      
const char* b = (const char*)msg[1];

It seem there is no value when I test by printf

I'm going to use it this way

char test[20];
strcpy(test, a);
strcat(test, ",");
strcat(test, b);
strcat(test, "\0");
mclient.publish("topic1/sensorAck",test);

The result show only comma

Codes less that 32 are control codes, 0x1 that is the value of *a is not printable. — NetVipeC, Jul 29 '14 at 13:24
You are casting to const char *, but what you do with it is wrong. 1 and 2 are not printable ASCII characters and you also need to be aware of the endianness of the system. Are you trying to convert an integer into a string? — Neil Kirk, Jul 29 '14 at 13:24
that is what am I going to do in the question I want to sent message via test variable the data should be something like "1,23" and raw data is come by int[] msg so I need to extract it and combine it as char* because function require that — Jongz Puangput, Jul 29 '14 at 13:31
Are you saying you want to convert integers to strings? Do you understand the difference between the number `1` and the string `"1"`? — Neil Kirk, Jul 29 '14 at 13:33
const char* a = (const char*)msg[0]; this is not mean I convert it to string ?? ("1") — Jongz Puangput, Jul 29 '14 at 13:34
so, what should I do please advice the msg[0] is any number as you see 1 so , how can I get "1" — Jongz Puangput, Jul 29 '14 at 13:37
@JongzPuangput http://stackoverflow.com/questions/10847237/how-to-convert-from-int-to-char — carloabelli, Jul 29 '14 at 13:38

score 1 · Answer 1 · answered Jul 29 '14 at 13:23

1

strcpy and strcat both stop when they reach a '\0' character in the source string. Since int 1 is actually 4 bytes (0, 0, 0, 1), it will stop on the first byte, because it's zero '\0' and never reach the '1' value byte.

answered Jul 29 '14 at 13:23

ben

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4

2

It depends on the endianness of the system. It may reach 1 first. – Neil Kirk Jul 29 '14 at 13:24

score 0 · Accepted Answer · answered Jul 29 '14 at 13:47

0

Here's the C code to convert an integer into a C string.

int i = 1;
char text[12];
sprintf(text, "%d", i);

answered Jul 29 '14 at 13:47

Neil Kirk

21,327
9
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result is this "ê" instead of "1" – Jongz Puangput Jul 29 '14 at 13:50

how to cast int from int[] to const char*

2 Answers2