c - Reading multiple values from formatted string using sscanf -


i'm trying extract 2 values string. first 8 digit hexadecimal value, , second unsigned 1-4 digit value. values should preceded command tells program values, in case "read". examples of format:

"read 0x1234abcd 2000" "read 0x00000001 10"

i want both extract 2 values , confirm format, , have following lines of code:

uint addr; uint len;  int n = sscanf(str, "read 0x%x[0-9a-fa-f]{8} %u[0-9]{1,4}", &addr, &len);  if (n != 2){     // wrong format... }

the hex-value read correctly, second value not , n 1. doing wrong?

what doing wrong?

input:  "read 0x1234abcd 2000" format: "read 0x%x[0-9a-fa-f]{8} %u[0-9]{1,4}"

input "read 0x" matches format "read 0x". far.

input "1234abcd" matches format "%x". far. +1 return value.

input " " not match format "[". scanning stops. sscanf() returns 1.

alternatives, read 2nd value decimal value.

const char *f1 = "read 0x%x %u"; const char *f2 = "read 0x%x%u";   // space not need, yet looks const char *f3 = "read %x%u";     // read addr hex, with/without 0x const char *f4 = "read %x %u"; const char *f5 = "read%x%u";  unsigned addr; unsigned len; int n = sscanf(str, fn, &addr, &len);  // select format above

the above code not fail

"read 0x0x123 +1234" "read 0x123 456 xyz" "read 0x123 12345" "read 0x+123 -123"

should op want more error checking. 8 limits text input addr 8 non-white-space characters. sentinel detects tailing non-white-space garbage.

unsigned addr; unsigned len; char sentinel; int n = sscanf(str, "read 0x%8x %4u %c", &addr, &len, &sentinel); if (n != 2){   // wrong format... }

the above fail 

"read 0x123 456 xyz"

what closest op original code obliges more work. use "%[...]" test allowable scan set.

#define f_rd    "read" #define f_sp    "%*[ ]" #define f_addr  "0x%8[0-9a-fa-f]" #define f_len   "%4[0-9]" #define f_sen   " %c" char addr_s[8+1]; char len_s[4+1]; char sentinel; int n = sscanf(str, f_rd f_sp f_addr f_sp f_len f_sen, addr_s, len_s, &sentinel); if (n == 2){   // success   unsigned long addr = strtoul(addr_s, (char **)null, 16);   unsigned len = strtoul(len_s, (char **)null, 10);   ... }

i see no line of input code not fail/pass op might desire, except allow x or x.


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