{"id":1323,"date":"2023-02-03T12:43:31","date_gmt":"2023-02-03T12:43:31","guid":{"rendered":"https:\/\/ibex.tech\/c\/?p=1323"},"modified":"2024-06-07T15:33:37","modified_gmt":"2024-06-07T14:33:37","slug":"printf","status":"publish","type":"post","link":"https:\/\/ibex.tech\/c\/c\/console\/printf","title":{"rendered":"printf"},"content":{"rendered":"\n
#include <stdio.h><\/code><\/pre>\n\n\n\n
Remember to include a terminating \u201c\\n\u201d in your printf \u2013 stdout doesn\u2019t flush until it encounters one by default!!!!<\/mark><\/strong><\/em><\/p>\n\n\n\n
If printf still doesn’t occur you may need fflush(stdout); or consider using std::cout instead<\/mark><\/strong><\/em><\/p>\n\n\n\n
\tprintf(\"Hello world!\\n\");\n\n\tprintf(\"%i bytes read : %s\\n\", rx_length, rx_buffer);\n\n\tprintf(\"data_h: %02X\\n\", sensor_data_h);<\/code><\/pre>\n\n\n\n
printf format codes<\/h5>\n\n\n
bool %d
int %d
int %i
int8_t %hhd
uint8_t %hhu
int16_t %hd
uint16_t %hu
int32_t %ld
uint32_t %lu
int64_t %lld
uint64_t %llu
char[] %s
float %f (Decimal floating point)
float %.3f (3 represents the number of digits after the decimal separator)
float %e (Scientific notation (mantissa\/exponent), lowercase)
float %g (Use the shortest representation:\u00a0%e<\/tt>\u00a0or\u00a0%f<\/tt>)
double %lf (up to 6 digits of precision using standard decimal notation, without any trailing zeros)
double %lg (up to 6 digits of precision which can use scientific notation if its shorter)

\/\/Displaying hex:
uin16_t 0x%04X (display 4 characters of hex)

\/\/Alternative bool
printf(\"%s\", x ? \"true\" : \"false\");


<\/pre>\n\n\n
d or i \u2013 int, decimal (base ten) number<\/p>\n\n\n\n
x or X \u2013 int, hexadecimal number.  Also \u201c%02x\u201d to specify length of digits<\/p>\n\n\n\n
ld \u2013 long, decimal number (\u2018l\u2019 can also be applied to any of the above to change the type from \u2018int\u2019 to \u2018long\u2019)<\/p>\n\n\n\n
u \u2013 unsigned, decimal number<\/p>\n\n\n\n
lu \u2013 unsigned long, decimal number<\/p>\n\n\n\n
llu \u2013 unsigned long long, decimal number (uint64_t)<\/p>\n\n\n\n
c \u2013 char, single character<\/p>\n\n\n\n
s \u2013 char pointer, string<\/p>\n\n\n\n
f \u2013 float, number with six digits of precision
g \u2013 float, number with up to six digits of precision
e \u2013 float, number with up to six digits of precision, scientific notation
lf \u2013 double, number with six digits of precision
lg \u2013 double, number with up to six digits of precision
le \u2013 double, number with up to six digits of precision, scientific notation<\/p>\n\n\n\n
Including values examples<\/h4>\n\n\n\n
Hex values<\/h5>\n\n\n\n
\t\/\/Include a 2 digit HEX value \"%02\"\n\tprintf(\"MyValue: 0x%02X\\n\", (uint16_t)SwitchInputs);\n\n\t\/\/Include a 4 digit HEX value \"%04\"\n\tprintf(\"MyValue: 0x%04X\\n\", (uint16_t)SwitchInputs);<\/code><\/pre>\n\n\n\n
Int values<\/h5>\n\n\n\n
\t\/\/Force to 2 digits\n\tprintf(\"MyValue: %02i\\n\", (uint16_t)TimeHours);<\/code><\/pre>\n\n\n\n
Result of an operation<\/p>\n\n\n\n
\tprintf((err != ESP_OK) ? \"Failed!\\n\" : \"Done\\n\");<\/code><\/pre>\n\n\n\n
printf in a multi-thread environment<\/h4>\n\n\n\n
Watch out for clashes causing bugs!  This can happen with irq\u2019s using printf, different threads using it, etc.<\/p>\n\n\n\n
Using a semaphore to protect<\/h5>\n\n\n\n
This is one option to stop clahses, e.g.<\/p>\n\n\n\n
#include \"semphr.h\"\n\n\/\/Create semphore\nSemaphoreHandle_t print_semaphore = NULL;\n\n\tprint_semaphore = xSemaphoreCreateMutex();\n    \n    \n\/\/Use sempahore\n\txSemaphoreTake(print_semaphore, portMAX_DELAY);\n\tprintf(\"Something\");\n\tprintf(\"Something\");\n\txSemaphoreGive(print_semaphore);<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
Remember to include a terminating \u201c\\n\u201d in your printf \u2013 stdout doesn\u2019t flush until it encounters one by default!!!! If printf still doesn’t occur you may need fflush(stdout); or consider using std::cout instead printf format codes bool %dint %dint %iint8_t %hhduint8_t %hhuint16_t %hduint16_t %huint32_t %lduint32_t %luint64_t %llduint64_t %lluchar[] %sfloat %f (Decimal floating point)float %.3f (3 represents the number […]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[111,113],"tags":[],"class_list":["post-1323","post","type-post","status-publish","format-standard","hentry","category-console","category-console-c-2"],"_links":{"self":[{"href":"https:\/\/ibex.tech\/c\/wp-json\/wp\/v2\/posts\/1323","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ibex.tech\/c\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ibex.tech\/c\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ibex.tech\/c\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/ibex.tech\/c\/wp-json\/wp\/v2\/comments?post=1323"}],"version-history":[{"count":22,"href":"https:\/\/ibex.tech\/c\/wp-json\/wp\/v2\/posts\/1323\/revisions"}],"predecessor-version":[{"id":1579,"href":"https:\/\/ibex.tech\/c\/wp-json\/wp\/v2\/posts\/1323\/revisions\/1579"}],"wp:attachment":[{"href":"https:\/\/ibex.tech\/c\/wp-json\/wp\/v2\/media?parent=1323"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ibex.tech\/c\/wp-json\/wp\/v2\/categories?post=1323"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ibex.tech\/c\/wp-json\/wp\/v2\/tags?post=1323"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}