Character String Manipulation

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Character String Manipulation
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Overview

• Character string functions
• sscanf() function
• snprintf() function

3
Some Character String Functions
double atof(const char string) - Converts
string into a floating point value int atoi(const
char string) - Converts string into an int
value char strncat(char s1, const char s2,
size_t count) - Appends up to count characters
of s2 onto the end of s1char strchr(const char
s, int c) - Searches for first occurrence of
c in s. Returns a pointer to c or NULL int
strncmp(const char s1, const char s2, size_t
count) - Compares up to count characters of s1
to s2. Returns 0 if they are identicalchar
strncpy(char s1, const char s2, size_t
count) - Copies up to count characters of s2
onto s1size_t strlen(const char s) - Returns
the number of characters in s not counting
\0char strtok(char s1, const char s2) -
Extracts tokens from string s1 based on token
separators in s2
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sscanf() Function

• include ltstdio.hgtint sscanf(const char
  buffer, const char format, )
• The sscanf() function is identical to scanf()
  except that data is read from the array pointed
  to by buffer rather than stdin
• The return value is equal to the number of
  variables that were actually assigned values
• A value of zero means that no fields were
  assigned any values
• As a side note, there is also an snscanf()
  function, but it is not standardized in C

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snprintf() Function

• include ltstdio.hgtint snprintf(char buffer,
  int size, const char format, )
• The snprintf() function is identical to printf()
  except that the output is put into the array
  pointed to by buffer instead of being written to
  stdout
• The array pointed to by buffer should already be
  allocated
• The return value is equal to the number of
  characters actually placed into the array
• The size parameter provides a bounds check on the
  array pointed to by buffer. It is the maximum
  number of characters that will be written to the
  buffer

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Example use of strncpy(), sscanf() and snprintf()
include ltstdio.hgt define MAX_LENGTH 100 int
main(void) char stringAMAX_LENGTH char
stringBMAX_LENGTH int count float
costPerItem int binNbr char nameMAX_LENGTH fl
oat totalCost
(More on next slide)
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Example use strcpy(), sscanf() and sprintf()
strncpy(stringA, "103 67.4 35bottle,
MAX_LENGTH) sscanf(stringA, "d f ds",
count, costPerItem, binNbr,
name) fprintf(stderr, "Input data d .2f d
s\n\n", count, costPerItem, binNbr,
name) totalCost count costPerItem snprintf
(stringB, MAX_LENGTH, "d s items
.2f per s .2f", count, name,
costPerItem, name, totalCost) printf("Computatio
n for Bin d\n, binNbr) printf( s\n",
stringB) return 0 // End main
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Sample output
Input data 103 67.40 35 bottle Computation for
Bin 35 103 bottle items 67.40 per bottle
6942.20
?