diff --git a/node.go b/node.go
index 7acb79a..b47915a 100644
--- a/node.go
+++ b/node.go
@@ -1006,7 +1006,7 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 
 		} else if funcName == `explode` {
 			if len(callParams) != 2 {
-				return "", parseErr{n, fmt.Errorf("Call to \\explode() should have 2 arguments, got %d", len(callParams))}
+				return "", parseErr{n, fmt.Errorf("Call to '%s' expected 2 argument(s), got %d", funcName, len(callParams))}
 			}
 			this.importPackages["strings"] = struct{}{}
 			funcName = `strings.Split`
@@ -1014,13 +1014,87 @@ func (this *conversionState) convertNoFreeFloating(n_ node.Node) (string, error)
 
 		} else if funcName == `implode` {
 			if len(callParams) != 2 {
-				return "", parseErr{n, fmt.Errorf("Call to \\implode() should have 2 arguments, got %d", len(callParams))}
+				return "", parseErr{n, fmt.Errorf("Call to '%s' expected 2 argument(s), got %d", funcName, len(callParams))}
 			}
 
 			this.importPackages["strings"] = struct{}{}
 			funcName = `strings.Join`
 			callParams[0], callParams[1] = callParams[1], callParams[0] // need to reverse function argument order
 
+		} else if funcName == `sprintf` {
+			this.importPackages["fmt"] = struct{}{}
+			funcName = `fmt.Sprintf`
+
+		} else if funcName == `trim` {
+			if len(callParams) != 1 {
+				return "", parseErr{n, fmt.Errorf("Call to '%s' expected 2 argument(s), got %d", funcName, len(callParams))}
+			}
+
+			this.importPackages["strings"] = struct{}{}
+			funcName = `strings.TrimSpace`
+
+		} else if funcName == `rtrim` {
+			if len(callParams) != 1 {
+				return "", parseErr{n, fmt.Errorf("Call to '%s' expected 1 argument(s), got %d", funcName, len(callParams))}
+			}
+
+			this.importPackages["strings"] = struct{}{}
+			this.importPackages["unicode"] = struct{}{}
+			funcName = `strings.TrimRightFunc`
+			callParams = append(callParams, `unicode.IsSpace`)
+
+		} else if funcName == `ltrim` {
+			if len(callParams) != 1 {
+				return "", parseErr{n, fmt.Errorf("Call to '%s' expected 1 argument(s), got %d", funcName, len(callParams))}
+			}
+
+			this.importPackages["strings"] = struct{}{}
+			this.importPackages["unicode"] = struct{}{}
+			funcName = `strings.TrimLeftFunc`
+			callParams = append(callParams, `unicode.IsSpace`)
+
+		} else if funcName == `strtolower` {
+			if len(callParams) != 1 {
+				return "", parseErr{n, fmt.Errorf("Call to '%s' expected 2 argument(s), got %d", funcName, len(callParams))}
+			}
+
+			this.importPackages["strings"] = struct{}{}
+			funcName = `strings.ToLower`
+
+		} else if funcName == `strtoupper` {
+			if len(callParams) != 1 {
+				return "", parseErr{n, fmt.Errorf("Call to '%s' expected 2 argument(s), got %d", funcName, len(callParams))}
+			}
+
+			this.importPackages["strings"] = struct{}{}
+			funcName = `strings.ToUpper`
+
+		} else if funcName == `file_put_contents` {
+			if len(callParams) != 2 {
+				return "", parseErr{n, fmt.Errorf("Call to '%s' expected 2 argument(s), got %d", funcName, len(callParams))}
+			}
+
+			this.importPackages["io/ioutil"] = struct{}{}
+			funcName = `ioutil.WriteFile` // (string filename, []byte data, int perm)
+
+			callParams[1] = `[]byte(` + callParams[1] + `)`
+			callParams = append(callParams, `0644`) // default file permissions
+
+		} else if funcName == `str_replace` {
+			// str_replace( mixed $search , mixed $replace , mixed $subject [, int &$count ] )
+			// n.b. str_replace also supports arrays, that strings.Replace() doesn't do
+			if !(len(callParams) == 3 || len(callParams) == 4) {
+				return "", parseErr{n, fmt.Errorf("Call to '%s' expected 3 or 4 argument(s), got %d", funcName, len(callParams))}
+			}
+
+			this.importPackages["strings"] = struct{}{}
+			funcName = `strings.Replace` // (s, old, new string, n int) string
+			callParams[0], callParams[1], callParams[2] = callParams[2], callParams[0], callParams[1]
+
+			if len(callParams) == 3 {
+				callParams = append(callParams, `-1`) // replaceAll
+				// There is a strings.ReplaceAll() added in go1.12 (2018), which is still pretty recent i.e. not in Debian Stable (buster)
+			}
 		}
 
 		return funcName + "(" + strings.Join(callParams, ", ") + ")", nil // expr only, no semicolon/newline